Null Reference Exception issue

Apr 23, 2009 at 1:44 PM

I'm getting an error which I can't figure out why.

I'm working with the Facebook Developer Toolkit and the useful VS 2008 starter kit (from Steve Trefethen).

When I first call my canvas page, the following code works fine and gives the string of the image url:-

However, if I navaigate to a different page and then navigate back to my original canvas page, the same line of code produces a 'NullReferenceException'?

I'm using

Any thoughts or explanations would be much appreciated.