Problems with avrdude

Hi,

I get a new error:

avrdude: Yikes!  Invalid device signature.
         Double check connections and try again, or use -F to override
         this check.

I've followed the instructions again and just wrote add("-F') and now I get a

avrdude: Yikes!  Invalid device signature.
avrdude: Expected signature for ATMEGA168 is 1E 94 06

Suggestions?

Regards, Michael