Using multi-language resources

I am trying to embed language resources in my plugin and receive the following error message in Grasshopper:

XYZ:Could not find any resources appropriate for the specified culture or the neutral culture. Make sure “XYZ.Resources.Languages.Lang.resources” was correctly embedded or linked into assembly “XYZ” at compile time, or that all the satellite assemblies required are loadable and fully signed.

Build action for these resources is set to EmbeddedResource.

Any ideas how this could be solved?

Is that an error message during startup, command line or are they in a window?

Can you send me the GHA so I can try and replicate the exception in my debugger?