Problem with UI for a RIG

Hello, i'm introducing myself to maxscripting by doing User Interface for my rig. I have a button added with custom attributes to my master controller and i want this button to pop my ui dialog. It works ok as long as i run the whole ui script first. If i reset max and pick the same buton got:
"Call needs function or class, got: undefined" Can u please explain to me how to make this working without having to run script first?
Below is my script, i tried to move rollout in diffrent places but it didnt help :| It would be cool if u could tak a look (deleted functions and stuf to make it readable ;)):