PIX VPN issue

I have a VPN established with a vendor of ours that has worked perfectly for years. 2 days ago the vendor request that we allow another subnet to access our network. I added the subnet to an ACL and tested from my end. I was able to ping the host that would access our network. I assumed everything was fine but when the vendor tested he was unable to connect (ping, ftp, tracert, etc.). I did not change anything with encryption or authentication (we are using 3DES and MD5, pre-share key). We even went over the settings again to make sure each end matched. Also, he is still able to connect using his other subnet that has worked for years. The only issue is with the new subnet, and again, i am able to access it, he is not able to access ours. Any ideas?