Remote access to MS SQL

I can connect remotely with Enterprise Manager just fine. However, we have a desktop app that we use to update our online store about twice a week and it's failing to connect. Is there anything special about remote access to DiscountASP.Net MS SQL server? Support said it should work but to ask out here for specifics.

The desktop app works great on all the other servers we're currently using including EasyCGI.

I'm not posting an error because the program right now just gives a generic error. We'll add error checking but I just wanted to ask if there was anything special.