Gen Tasklist upload using LSMW

Hi,

I am trying to upload General task list using LSMW standard object 0490. I am using internal no. range for task list. While uploading, system assigns internal group no. to first record but for further records it is creating different group counter.

My requirement is to create different group no. for different records. For this I tried with giving blank value in the field PLNNR, but its not working.

Please suggest.

Thanks,

Hitesh Mistry