Epim pro network trial version problem

I cannot set Comodo to allow firebird server to access client programs on another machine. I use W2K sp3, [mch1] and a program called EssentialPIM or EPIM network version on a W98 [mch2] . Firebird is used to connect one epim datafile to 2 pcs on a network. I can get the client [mch2] to connect to fbserver when I set CPF [on mch 1 ] to allow all. When I use “custom” I cannot connect. The port used is 3050. When I go to “Applications Monitor” I see that Firebird fbserver seems to have the necessary permissions. Mch2 has no firewall. Can you help?