dotCover unable to load dll Follow

We're referencing Microsoft.SqlServer.Types.dll in our .Net solution (2 projects).

This dll internally depends on SqlServerSpatial.dll (which can be found in both SysWow64 dir and Sytem32 dir).

We have tests which test implementations using a type from Microsoft.SqlServer.Types.dll and up until now have been executing with no problems (MSTest / Visual Studio runner AND fine in nCrunch) however we thought we'd trial dotCover and are getting an error on these tests: "Unable to load DLL: SqlServerSpatial.dll"

If we try and include the file in the project build output we get a System.BadImageFormatException instead.

Any ideas why dotCover cannot load the type but ncrunch/vs test runner can? Showstopper for us being able to use dotCover...