Label and button question

OK so I feel real stupid asking this question but for some reason I am unable to figure it out.  I have a VS2010 VB.Net app.  There is a button and a label on the page.  When I get no data back from the DB I set the label.  What I can't figure out is the fact I need to clear the label the next time the button is pressed.  Here is what I have tried:
1 - Putting the label in an update panel
2 - setting the text to "" on post back
3 - setting the text to "" in the button click event.
I cringe because I am sure it is a simple solution. :D