Loading/starting a Mod by doubleclicking the save file

[srad]

This question is related to the HOF / Buffy Mod but I guess it also a general technical question:

Since I'm running the Steam Civ versions it is no more possible to launch Civ with the correct Mod when double clicking the save file. Civ starts but the save is not loaded and also not the mod.

Anyone knows what I need to do to achieve this behavior?

Operating system is Win7 64bit and it is the Steam Civ version.

Thanks for help!