MSBuild (the default tool the Make VS.NET action uses to build VS2005 projects/solutions) doesn't know how to build .wsproj files. Configuring the Make VS.NET action to build via devenv instead of msbuild (select or enter 'devenv' in the 'Override the default location...' field on the Options tab) should cause the solution to build properly.
http://www.visualbuild.com/Manual/vsnetoptionstab.htm
Or request that Wise and/or MS extend MSBuild to support .wsproj files.