At the time I wrote this question I was unaware of DNS requirements for multiple IPs, but read about people having to create DNS entries into their dns servers, hence the question. We do have two public IP addresses. Caching appeared to be hit or miss and I was racking my brain why. After reading Antonio's links I quickly realized that DNS entries would be required for us because, well, we do have two IPs (I felt dumb on that one :-) ).
I have temporarily set it to server "all networks" and it is working in a hit or miss fashion, but it is working. I am working on some other things at the moment, but when I get back to Caching early next week I will be researching the process for Multiple IPs and multiple VLANS...
thanks for the replies. I will mark the question solved as soon as I get it working.