Outlook Web Access error msg

My remote have no problem accessing a tunnel to our LAN. the problem/error occurs when they try to access the Exchange server. When they do a ‘get’ for http://192.206.12.3/Exchange which should bring up the Web Access Logon page, they get this error:

error ‘ASP 0115’
unexpected error
/exchange/USA/logon.asp
A trappable error occured in an external object.
the script cannot continue running.

My LAN has a Web server. The Exchange server has IIS and Web Access installed.

any ideas regarding this error would be appreciated.

Thanks