Look at the release notes for 1.4.10 (a curious version to use BTW,
why not go ahead and use 1.4.62?), and note that that is when the RPC
system went through some significant changes - as did other things, it
was the first RC for 1.4.
http://code.google.com/webtoolkit/releases/release-notes-1.4.62.html
Scroll down the 1.4.10 part, see the changes.
And turn up your shell logging, should be able to see exactly what is
failing in the console.