Vassal would not read vdmx files

[otto]

They are all unzipped and I tried one by one.
Actually starting from the core data minefields file
I've never played the PG Vassal before and I decide to start from (...obviously :-)) the Fronte Russo module with the intention of playing two scenarios and submitting their log file.
I downloaded and unzipped it jointly with all the required vdmx files.
I wonder if adding the vdmx estension does not work because I lack some permission.