Need cacti MRTG graphs working again

2 Problems Problem 1: I replaced my master switch and MRTG graphs disappeared for all switches behind it, and I am not getting MRTG graphs for that. Problem 2: When it was working the graphs for one of the switch were intermitent. Please describe your experience with Cacti and if you have come across those two problems before. You will not have telnet access to my switches but I will show you the running config and run commands as needed. This is the snmpwalk output from my master switch: # snmpwalk -c xxxxxxx -v 2c [login to view URL] system SNMPv2-MIB::sysDescr.0 = STRING: Cisco IOS Software, C2960 Software (C2960-LANBASE-M), Version 12.2(35)SE5, RELEASE SOFTWARE (fc1) Copyright (c) 1986-2007 by Cisco Systems, Inc. Compiled Thu 19-Jul-07 20:06 by nachen SNMPv2-MIB::sysObjectID.0 = OID: SNMPv2-SMI::enterprises.9.1.717 DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (115520235) 13 days, 8:53:22.35 SNMPv2-MIB::sysContact.0 = STRING: SNMPv2-MIB::sysName.0 = STRING: [login to view URL] SNMPv2-MIB::sysLocation.0 = STRING: SNMPv2-MIB::sysServices.0 = INTEGER: 2 SNMPv2-MIB::sysORLastChange.0 = Timeticks: (0) 0:00:00.00