Use the PrintTask_CSharp.dll from the Debug folder (e.g., <a href="file:C:/.../650927/Test0708/Common_PrintTask/CSharp/Common_PrintTask_CSharp/PrintTask_CSharp/bin/Release)" target="_blank">C:\...\650927\Test0708\Common_PrintTask\CSharp\Common_PrintTask_CSharp\PrintTask_CSharp\bin\Release)</a> and not the Release folder when adding the new tool to toolbar using ‘Choose Items…’.