Asterisk AMI auth / logging

We are using the AMI for custom software to manage queues and such. Software is written using Asterisk.Net

we have the program running fine on the network the Asterisk box is on and also from a remote office using VPN.

Now we tried to run it from another remote office using VPN and we are getting an authentication error when trying to log in to the AMI.

Is there anything I can use to find out what the issue might be such as a log file on the asterisk server ?

thanks

Mike