Window MAIN is not defined for form ZXXXX

Hi,

Our SAP ver has upgraded from 4.6C to ECC6, in ECC6 while testing payment run in background job got an error i.e.

"Window MAIN is not defined for form Z110_US_DTA".

It is a custom script in 4.6C is working fine, but we did not make any changes and tested in ECC6, got the above said error.

Could you help on this how to correct this error, why this error is occuring and what situations it will come.

Regards,

Ganesh