diff --git a/src/ConfigTransfer.script.js b/src/ConfigTransfer.script.js
index cf9ae47..f6038e2 100644
--- a/src/ConfigTransfer.script.js
+++ b/src/ConfigTransfer.script.js
@@ -247,17 +247,19 @@ function _uctBtnCopy(device, online, progress, context) {
     if (mode == 0) {
         var sourceChannel = device.getParameterByName(context.p_channelSource).value;
         var targetChannels = uctParseRangesString(device.getParameterByName(context.p_channelTargetString).value);
+        if (targetChannels.length == 0) {
+            throw new Error('Kein Ziel-Kanal definiert!');
+        }
+        // => targetChannels are NOT empty
+
         Log.info("OpenKNX ConfigTransfer: Copy single channel " + sourceChannel + " to " + targetChannels.join(","));
         uctProgressText(progress, "Kanalkopie " + module + "/" + sourceChannel + " -> " + targetChannels.join(","));
 
         // precheck channels:
-        // uctGetModuleParamsDef(module, targetChannel[targetChannel.length - 1]);
-        if (targetChannels.length > 0) {
-            // ignore result, but expect error for non-existing channel
-            uctGetModuleParamsDef(module, targetChannels[targetChannels.length - 1]);
-            if (!uctIsDisjoint([sourceChannel], targetChannels)) {
-                throw new Error('Quell- und Ziel-Kanal dürfen NICHT identisch sein!');
-            }
+        // ignore result, but expect error for non-existing channel
+        uctGetModuleParamsDef(module, targetChannels[targetChannels.length - 1]);
+        if (!uctIsDisjoint([sourceChannel], targetChannels)) {
+            throw new Error('Quell- und Ziel-Kanal dürfen NICHT identisch sein!');
         }
 
         // inline without duplicate export: result.push(uctCopyModuleChannel(device, module, sourceChannel, targetChannels[i]));
@@ -278,24 +280,27 @@ function _uctBtnCopy(device, online, progress, context) {
         uctProgress(progress, 97);
     } else if (mode == 1) {
         var sourceChannels = uctParseRangesString(device.getParameterByName(context.p_channelSourceString).value);
+        if (sourceChannels.length == 0) {
+            throw new Error('Kein Quell-Kanal definiert!');
+        }
+
         var targetChannel = device.getParameterByName(context.p_channelTarget).value;
         var offset = targetChannel - sourceChannels[0];
         Log.info("OpenKNX ConfigTransfer: Copy channel group " + sourceChannels.join(",") + " to channels starting at " + targetChannel + "; offset=" + offset);
         uctProgressText(progress, "Kanalkopie " + module + "/" + sourceChannels.join(",") + " -> ...");
 
-        if (sourceChannels.length > 0) {
-            // ignore result, but expect error for non-existing channel
-            uctGetModuleParamsDef(module, sourceChannels[sourceChannels.length - 1]);
-        }
+        // ignore result, but expect error for non-existing channel
+        uctGetModuleParamsDef(module, sourceChannels[sourceChannels.length - 1]);
 
         var targetChannels = [];
         for (var i = 0; i < sourceChannels.length; i++) {
             targetChannels.push(sourceChannels[i] + offset);
         }
-        if (targetChannels.length > 0) {
-            // ignore result, but expect error for non-existing channel
-            uctGetModuleParamsDef(module, targetChannels[targetChannels.length - 1]);
-        }
+        // sourceChannels NOT empty => targetChannels NOT empty
+
+        // ignore result, but expect error for non-existing channel
+        uctGetModuleParamsDef(module, targetChannels[targetChannels.length - 1]);
+
         uctProgressText(progress, "Kanalkopie " + module + "/" + sourceChannels.join(",") + " -> " + targetChannels.join(","));
         uctProgress(progress, 1);
 
diff --git a/src/ConfigTransfer.share.xml b/src/ConfigTransfer.share.xml
index 7fbc390..0a8c112 100644
--- a/src/ConfigTransfer.share.xml
+++ b/src/ConfigTransfer.share.xml
@@ -281,9 +281,9 @@
               <Parameter Id="%AID%_P-%TT%00300" Name="CopyModul"             ParameterType="%AID%_PT-ModuleSelectorWithChannels"          Text="Modul"                 Value="255" />
               <Parameter Id="%AID%_P-%TT%00306" Name="CopyMode"              ParameterType="%AID%_PT-CopyMode"                            Text="Kopier-Modus"          Value="0"   />
               <Parameter Id="%AID%_P-%TT%00301" Name="CopySource"            ParameterType="%AID%_PT-ModuleChannel"                       Text="Quell-Kanal"           Value="1"   />
-              <Parameter Id="%AID%_P-%TT%00304" Name="CopySourceString"      ParameterType="%AID%_PT-ChannelNot0SelectionString"          Text="Quell-Kanäle"          Value="1"   />
+              <Parameter Id="%AID%_P-%TT%00304" Name="CopySourceString"      ParameterType="%AID%_PT-ChannelNot0SelectionString"          Text="Quell-Kanäle"          Value=""    />
               <Parameter Id="%AID%_P-%TT%00302" Name="CopyTarget"            ParameterType="%AID%_PT-ModuleChannel"                       Text="Ziel-Kanal"            Value="1"   />
-              <Parameter Id="%AID%_P-%TT%00305" Name="CopyTargetString"      ParameterType="%AID%_PT-ChannelNot0SelectionString"          Text="Ziel-Kanäle"           Value="1"   />
+              <Parameter Id="%AID%_P-%TT%00305" Name="CopyTargetString"      ParameterType="%AID%_PT-ChannelNot0SelectionString"          Text="Ziel-Kanäle"           Value=""    />
               <Parameter Id="%AID%_P-%TT%00303" Name="CopyUserLog"           ParameterType="%AID%_PT-Text32KiB"                           Text=""                      Value=""    /><!-- Kopier-Resultat / Vorschau -->
               <Parameter Id="%AID%_P-%TT%00390" Name="CopyModulChannelCount" ParameterType="%AID%_PT-ModuleChannelCount"                  Text=""                      Value="0"   Access="Read" SuffixText="Kanäle" /><!-- Kanal-Anzahl im Modul -->
               <Parameter Id="%AID%_P-%TT%00391" Name="CopySourceError"       ParameterType="%AID%_PT-CheckBox"                            Text="Fehler: Quell-Kanal"   Value="0"   Access="None" />