custom list field design problem

I have added three custom listfield on a single screen which are separated by some space and labels. I have also drawn a roundrect on each row. The problem that i am facing is, whenver the first row of each listfield is diaplayed off the screen, the bottom line of round rect of that field also disappears. And this is happening for all the listfields. I have also invalidated all the listfields during focus and unfocus but 开发者_StackOverflowthe same problem is occurring.

please suggest something..............