Handling errors in eConnect has always been just a little bit tricky, you need to explicitly trap for the specific errors that it throws or you will get very cryptic messages. Here is the code that I'm using to trap communications with the eConnect WCF service. You'll need to add code to handle the exception... but this is a starter. Note that the first 'catch' refers to 'ex.detail(0).message', and the second to 'ex.detail.message'. I've not seen those constructs before.