I just tried this and there is a minor bug there. Funny but for me it did not cause any problem in any browser using IIS, but when I tried it in the VS web server using IE 8 I got an error from a debug assert that compares the passed in sql paramter type to the one reported by the stored proc. In code it was mistakenly declared as NChar 20 when it really should be NVarChar 20.
I will correct the release package asap by replacing only the mojoPortal.Data.dll.
Note however that I think you must be running your own build possibly compiled in debug mode rather than release mode and/or maybe you have <compilation debug="true" in your Web.config. Otherwise I "think" this debug.assert would not fire and that is what causes the actual error. Sql server I think is a little more forgiving of mismatched params.
Hope it helps,