Hi there!
The problem is that you need to supply "The assembly-qualified name of
the type to get. [...] If the type is in the currently executing
assembly or in Mscorlib.dll, it is sufficient to supply the type name
qualified by its namespace." (see
http://msdn.microsoft.com/en-us/library/w3f99sx1%28loband%29.aspx)
So try this instead...
<errorFilter>
<test>
<or>
<is-type-compatible binding="BaseException"
type="System.Web.HttpException, System.Web,
Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
</or>
</test>
</errorFilter>
Cheers,
James