Primary reference Florentis.InteropFlSigCapt could not be resolved

The full message is:

Primary reference Florentis.InteropFlSigCapt could not be resolved because of an indirect dependency on the .NET framework assembly

This can happen if you build a .NET application targeted at framework 3.5 and try to include the interop DLLs from the Signature SDK which are built for 4.0.

The solution to this is to add references to the DLLs themselves and not the interop files.

As illustrated in the Reference Manager screenshot below references have been added to FlSigCOM.dll and FlSigCapt.dll – Visual Studio will then generate its own interop files for your target framework.

Remove any existing references to WacomGSS or Florentis interop files and then add the two shown with ticks below.

In the example below the target CPU is set to x86 which is why the DLLs have been selected from "C:/Program Files (x86)/Common Files/WacomGSS" and not "C:/Program Files/Common Files/WacomGSS"