Dynamically Changing A Picture At Runtime With VB.Net 2008

I have inserted a picture object into a Crystal Report and set the Graphic Location for that object to a parameter field which I have called "picPath". In my Vb.Net code I hard coded the location using the following line of code:

mReport1.SetParameterValue("picPath","C:\CustomerFile\Image01.jpg")

My problem is that this code works sometimes and other times it does not. I have also tried with and without the quotation marks around the path location which did not help. Any help resolving this issue would be greatly appreciated. Thanks.