Referencing external assemblies from PowerShell snap-in-Collection of common programming errors

SOLUTION (Posting it here as suggested by one of the comments to my question)

My problem was rather specific, as I’m developing on a 64 bits server machine, but I’m posting the solution in case it could help someone else as well.

Using fuslogvw as suggested, I saw that the dependent assembly was being searched using the machine.config file under C:\Windows\Microsoft.NET\Framework64 and then the binding failed; launching the project with “start without debugging”, instead, the machine.config file under C:\Windows\Microsoft.NET\Framework was taken (notice the missing 64 at the end).

I thought that the problem could be due to the image format, and infact the dependent assembly was being compiled with x86 as CPU target; I changed it to “Any CPU” and now the assembly is loaded correctly.