Like it says, you're not passing in the required inputs. How did you call it in your script or command window. If you did something like
message = 'Hello POTNURU!';
obj = HelperPoolWaitbar(N,message)
then you should not get that particular error. So, what are your N and message? If they're undefined (like you clicked the green run triangle before you assigned anything to N and message) then of course it won't know what to do and throw an error.