win98

I ‘ve just added a modem (crypto best II 56k pci) on an old pc (it is a P133 and runs on win98. The installation went Ok,it is there, but when i try to go on line it says that win98 can not find a modem or port may be shut/ installation not correct,and when i use modem->diagnostics win98 can not find either.
The divice manager says it is there and works correctly. Any suggestions please?
Thanks