2001 XC70 remote lock problems

I have a 2001 XC70 which has a problem with the remote locking system. I noticed about a year ago it would intermittently not work. I changed the battery in the remote and it did ok for a couple of weeks. It now only works maybe 1 in 50 times. Again I have changed the battery in the remote and each time I do this it will work the 1st time and maybe a few more times but then stops working. I have cleaned the contact points in the remote where the battery seats. It is not killing the batteries as they still check at a little over 3 volts when checked with a meter. It also seems to work a couple of times just by removing the battery from the remote and putting the same battery back in. Has anyone experienced this before?
Thanks in advance for any help.