Item getting copied from quotation to target transaction but cannot edit item

Hi Folks,

I created a follow-up transaction for quotation and did copy control in setting copy control for business transactions(checked complete reference).

Now follow-up document is getting created and pop up is coming to select the items.After I select item ,go to item assignment block and click on edit transaction gets struck.what could be probable reason for this behaviour?

Pls suggest.

Regards

Jaya.