多删除函数只删除中继器控件中的一行

i have 2 repeater controls one inside another, actually i am showing contents from two different tables, i have added checkboxes for each row to delete multiple rows using single button click, but after selecting multiple check boxes delete query deletes only one row at a time.i just added checkobx under repeater control, I tried to figure out the exception but stack doesnt show it!! following is my codebehind:i have 2 repeater controls one inside another,