Android Google App Engine OAuth difficulties

I have an Android / GAE application. We need to validate the Android user against GAE using OAuth.

We're currently using the Signpost library for this.

We've run through lots of the samples out there and we do seem to get a correct token.

Our problem is once we go to use that token to on our site - we get a 401 - Authorization Failed. The trace from GAE is below:

##TRACE##  APIBase:: authenticate() InvalidOAuthParametersError! 
    The client provided OAuth parameters with the request, but they are invalid.

We've tripple checked our consumer keys, and the other information and we don't know really where to do from here.

Does anyone have any Android to GAE examples that they've开发者_JAVA技巧 used successfully?

Thanks

I learned a lot from the Android2Cloud guys You can see how they do it at http://code.google.com/p/android2cloud/