Connecting FMSA to WPE

[mx4px]

Assuming that there are no TCP port restrictions, and the identifier & passcode are properly set up, can anyone think of any condition which would result in the following error message in trying to connect to FMSA from the web config console?

"Access to the specified FileMaker Server is restricted. Verify that this Publishing Engine is enabled in the FileMaker Server Administration Tool or specify an alternate server."

I've set these things up many times & never had this message. I'm stumped. I'm getting this when trying to set up WPE on IIS and on OS X/Apache (2 potential test servers in the same subnet...note that FMP has no trouble connecting to either of them).