I don't think that Picasa will recognize RAW files?
I use Picasa for importing and organizing my digital files--scans of my film and files from my digi-camera--but I don't shoot RAW, though I suppose I should, so I can't be sure.
Maybe, save a copy of your RAW file as a JPEG or TIFF and then you should see those in Picasa.
The path of excess leads to the tower of wisdom.
-- William Blake