linq conflict in update

Question

i have a listbox and  a textbox and a edit button.when i click an item in the listBox i see listbox's information in the textbox.
when i edit this text and click on edit button,some times work well but my listBox still show old information.i Bind listbox in btnEdit_click but it's not work right and when i click on the listbox i can see updated information in my textbox.
and sometimes when i click in edit button it can't update and show error.(conflict)
why don't it work rightly?