prob with airdrop

hi both my wife and i have early 2009 20 inch macs running the latest version of lion and 4 gb memory in each and it seems airdrop dosnt want to play, both macs are connected on the same wifi network with the virgin media superhub, and i have checked that our macs do support airdrop however i can see her mac on the airdrop screen and she can see mine however when trying to drop a file over to her computer i get the message that the file has been refused and it wont send over, however i scan the forum and saw the tip about force quiting the finder window and done this on both macs then airdrop may work for one "send" but when i try another after it refuses again we have not got a firewall turned on, on either mac and as for the computers being close we are about 6 feet away in the same room just wondering if there is any tips how we can get this feature to work