%dns variable in alerts

[Csanyi22]

We have recently setup PCM 4.  We previously were using PCM 2 and had no problems.  We have all the alerts working for when switch lose connection and the reconnect to the network.  The problem is we are using the $dns variable and it is coming up blank.  Example: the aler message is ($dns location is down) but the email we recieve just says (location is down).  If anyone has any suggestions that would be great.  One thing I did notice that may be part of the problem is under the Policy History. After reviewing the events in the history I can the that everything under the alert source is unknown. That is the IP, DNS, and MAC.  The all say uknown.  Not really sure where to go from here.

Thanks