Pagination Error CI

I have two webpages : http://ift.tt/1J9xNyb and http://ift.tt/1MpBuRv

Situation: I search a date : from this week up to today (based on the selection)

department.php: I click page 2, and the page works fine

newtest/sales I click page 2, and the pagination resets to its original maximum number of pages.

can somebody help me? tIA