can't create a skype folder don't have enough privileges

Since I install OS X 10.6.8 I can't download big programs like Skype or Google Chrome.

I downloaded skype, it will start the installation but at the end pop out a window saying that:

"can't create a skype folder at/user/v..../Library/Application Support/Skype.

mAKE SURE YOU HAVE ENOUGH PRIVILEGES TO CREATE THAT FOLDER AND LAUNCH SKYPE AGAIN"

I checked on Admin on my account and it says that can read and write so I don't understand why is not working

Can you help me pls?

Thanks

Valentina