InvalidOperationException: 变量不存在：txt1
StackTrace:
   在 Quicker.Domain.Actions.ActionExecuteContext.GetVarValue(String varName)
   在 DynamicClass.TimingFunction.<>c__DisplayClass4.<.ctor>b__0(Object s, EventArgs e)
   在 System.Windows.Threading.DispatcherTimer.FireTick(Object unused)
   在 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   在 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)