Mapping Folder within VPN

I have a VPN setup with a Cisco router. My internal network is setup with IP 111.111.111.0-254 and Mask 255.255.255.0. And for the VPN connection, IP are set to 222.222.222.0-254 with a Mask of 255.255.255.0. Within the VPN, I can ping to the Internal network without any problems. But I can’t use the “net use” command to map any network drive. Please help!