avrdude:invalid device signature error

i have a freeduino usb 1.1 board which has an atmega8a-pu microcontroller. upon uploading a code, i get the following error:

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

can anyone help?

Which board type are you selecting?
One of the NG types?

no, im selecting "freeduino usb 1.1 w/ atmega8" , the board which i have..