Missing Infor Window in INVOICE

Hi,

I am doing changes for INVOICE Prinitng by making a ZFORM,where I was able to handle almost all the windows but one of the WINDOW INFO1 [additional Information]where we need to pass SHIP to Details ,here I am able to see this window in LAYOUT but when I test it only this window is missing and even I checked in DEBUG mode this window will not appear only.

Can anyone let me know what did i missed here to get my INFO Window working.

Thanks

Sudharshan