function module with Pop up modal box

Hi everybody.

I have scenario to create a user defined function module like (pop_up_to_display_text) .

When user call the function module in a program, the function module takes values from program

and displays those values in pop up window(modal dialog box) . in that box a button is there.

when user clicks that button it takes to mm01 tcode .

I have tried copying the standard FM(pop_up_to_display_text) into zpopup fm . but after executing zpopup

I can neither cancel , nor close, nor leave the screen.

Please tell me how to approach.........................................