This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
Could you post more of the code, perhaps the whole method? Also, exactly which line are you getting the error on? I suspect that 'e' is out of scope where it is being used, or perhaps you have 'e' declared twice, but without seeing more of the code it is hard to tell.