Garageband update problems

Hi,

New to this world of MAC, so forgive me if I don't give enough infomation or... give too much. I checked my software update and found there was an update for Garageband, It is the GarageBand Instruments and Apple loops update version 1, it is 1.1 mb in size. when I try to download it, I get an error that the digital signature for this package is incorrect. I looked in here to find a solution and found one that told me to go to the wastebasked, pull the file out from there, extract the zip then run the file.

I have tried this many times and it is failing with the source media you are installing from is damaged.

I have deleted everything then redownloaded etc but still am having the same issue with it. I cannot suspect that Apple would give me a bad copy of a download, but I am at a loss to think of what else it could be.

can anyone assist??

thanks,

Swaff -)