Oracle Forms

Aslam o Alikum (Hi)

I am getting the problem that when i try to clear the elements of my list item "Product_ID" it is giving error message that

FRM-41331 Could not delete element from Product_ID

i am using following code

If Get_Item_Property( p_Product_List_Item , Update_Allowed) = 'TRUE' Then
Clear_List (p_Product_List_Item) ;
Else
Message ('update not allowed') ;
End If ;

Solution urgently required

Best Regards,
Nasir Zeeshan.