Error to Save item For particular User

hi, i added one onAfterAdd server event on item type  Part i have two user A and B i add this user to can Add and permission tab of Itemtype-Part and give same permission to user A and B but when i login to aras using user b i am able to create new part but not able to save it , it does not give any error but not save Part  itemtype but when i login through user A , i am able to save Part itemtype