not able to add target group in discount condition type in campaigns

Hi Guru's

i have a campaign discount condition type ZXYZ(usage PR, replicated from ECC), which has condition table with fields CAMPAIGN GUID/TARGET GROUP/PRODUCT.

When i select this condition type in discounts assignmnet block in campaigns and try to add Target group, im not able to add. i selected F4 but its says no entries. i entered the existing target group but it does take.

Can you let me know how to add the target group here.

Regards,

Kiran.