Are the Data DLL and other projects ALL set for the same Build type Release or Debug?
The default location for LIB files is OBJ\ Release or Debug so if you mix build types you can have an obsolete file. You can look in OBJ folder at the CwProj.FileList.Xml file to see the path of the LIB file being used.
See this post for how to move the LIB file to be written to the project folder with the DLL file: