diff --git a/src/modules/app.ts b/src/modules/app.ts
index 6f9e821..e3384e3 100644
--- a/src/modules/app.ts
+++ b/src/modules/app.ts
@@ -273,7 +273,7 @@ export default class App extends ModuleBase {
           ".rule": {
             write: 
               "auth.addr === $userAddress && getValue(`/apps/" + `${appName}` + "/balance/` + $userAddress + `/balance`) !== null && " +
-              "((getValue(`/apps/" + `${appName}` + "/billingConfig/` + $serviceName) !== null) && (getValue(`/apps/" + `${appName}` + "/balance/` + $userAddress + `/balance`)  >= getValue(`/apps/" + `${appName}` + "/billingConfig/` + $serviceName + `/minCost`)) || " +
+              "(!util.isEmpty(getValue(`/apps/" + `${appName}` + "/billingConfig/` + $serviceName + `/minCost`))) && (getValue(`/apps/" + `${appName}` + "/balance/` + $userAddress + `/balance`)  >= getValue(`/apps/" + `${appName}` + "/billingConfig/` + $serviceName + `/minCost`)) || " +
               "getValue(`/apps/" + `${appName}` + "/balance/` + $userAddress + `/balance`) >= getValue(`/apps/" + `${appName}` + "/billingConfig/service/default/minCost`)" 
           }
         }
@@ -290,19 +290,12 @@ export default class App extends ModuleBase {
         ref: Path.app(appName).billingConfig(),
         value: {
           ".rule": {
-            write: "util.isAppAdmin(`" + `${appName}` + "`, auth.addr, getValue) === true && util.isDict(newData) && " +
-            "util.isString(newData.depositAddress) && util.isDict(newData.service) && util.isDict(newData.service.default)",
+            write: "util.isAppAdmin(`" + `${appName}` + "`, auth.addr, getValue) === true && util.isDict(newData) && util.isString(newData.depositAddress) && " + 
+            "util.isDict(newData.service) && util.isDict(newData.service.default) && util.isNumber(newData.service.default.costPerToken) && util.isNumber(newData.service.default.minCost) && " + 
+            "util.isEmpty(newData.service.default.maxCost) || (util.isNumber(newData.service.default.maxCost) && newData.service.default.maxCost >= newData.service.default.minCost)",
           }
         }
       },
-      billingConfigOfService: {
-        ref: Path.app(appName).billingConfigOfService("$serviceName"),
-        value: {
-          ".rule": {
-            write: "util.isAppAdmin(`" + `${appName}` + "`, auth,addr, getValue) === true && util.isDict(newData) && util.isNumber(newData.minCost)",
-          }
-        }
-      }
     }
   }
 
diff --git a/src/modules/moduleBase.ts b/src/modules/moduleBase.ts
index 163d948..56789a9 100644
--- a/src/modules/moduleBase.ts
+++ b/src/modules/moduleBase.ts
@@ -32,25 +32,22 @@ export default class ModuleBase {
     return await this.ain.sendTransaction(txBody);
   }
 
-  private getFailedOpResultList(result: txResult): opResult[] {
+  private hasFailedOpResultList(result: txResult): boolean {
     if (result.result_list) {
-      return Object.values(result.result_list).filter(
+      return Object.values(result.result_list).some(
         (result: { code: number }) => result.code !== 0
       );
     }
-    return [];
+    return result.code !== 0;
   }
 
   private handleTxResultWrapper(operation: Function) {
     return async (args: any) => {
       const res = await operation(args);
       const { tx_hash, result } = res;
-      const failedOpResult = this.getFailedOpResultList(result);
-      if (failedOpResult.length > 0) {
-        const errorString = failedOpResult.map((value) => `\n code: ${value.code} - ${value.message}`);
-        console.log('failedOpResult :>> ', failedOpResult);
+      if (this.hasFailedOpResultList(result)) {
         throw new Error(
-          `Failed to send transaction (${tx_hash}).` + errorString
+          `Failed to send transaction (${tx_hash}).\n Tx Result: ${JSON.stringify(result)}`
         );
       }
       return tx_hash;
diff --git a/src/modules/wallet.ts b/src/modules/wallet.ts
index e585072..16dc8d4 100644
--- a/src/modules/wallet.ts
+++ b/src/modules/wallet.ts
@@ -62,6 +62,6 @@ export default class Wallet extends ModuleBase{
       throw new Error ("You need to add account");
     }
     txBody.address = signerAddress;
-    return await this.ain.sendTransaction(txBody);
+    return await this.sendTransaction(txBody);
   }
 }