AccessDenied SharePoint 2010 WebPart calling external Web Service through full-trust proxy

I do bother with 'Access Denied' error message while running SharePoint WebPart which in turn trigger external web service call. The web service proxy code is hosted within full-trust proxy. Now my web parts is SharePoint project scoped at site level and full-trust proxy implemenation lives in another SharePoint project scoped at farm level.

Whole stuff works like a charm while executed on dev machine but crashes in 开发者_如何学Cthe test environment. Dev machine is all-in-one SharePoint development environment with domain controller and kerberos.

test environment is ntlm staging environment.

What I am not seeing here? Any idea?

My understanding is that it is possible you are logged in while testing in dev with an administrator account. If your web part calls code that requires a certain level of access, another user may not be able to use it at all.