MSSQL Connect Issues

I've got 2 MSSQL db's I need to connect to.
Each DB is on a different box.
I'll call the servers serverA and serverB.

For some reason,
MSSQL_CONNECT("serverA",$user_name,$password);
works fine.

However,
MSSQL_CONNECT("serverB",$user_name,$password);
I get a unable to connect to server warning.

The only difference between the 2 servers is serverA is on a MSSQL 7 box and serverB is on a MSSQL 2000 box.

Any ideas?

It's a SQL Server setting. I know this because I used the same method to connect to a third MSSQL server and had no problems.

Therefore, I have 3 DB's, 2 of which I can connect to with the line.... must be the fault of the 3rd db.