Help with Check_SNMP issue

I have a newly installed Nagios 3.2.0 running on Ubuntu 9.04. I have moved our config files from our previous Nagios install to this server. Everything is working now, with the exception of check_snmp. All my check_snmp are coming back with a status of SNMP problem - No data received from host. When I run check_snmp from the command prompt I get the same error. I think the issue might be with the install NETSNMP on my machine. When I try to run SNMPGET or SNMPWALK from the command prompt I get the following errors…

snmpget: error while loading shared libraries: libnetsnmp.so.20: cannot open shared object file: No such file or directory

snmpwalk: error while loading shared libraries: libnetsnmp.so.20: cannot open shared object file: No such file or directory

Please advise on how I can resolve this issue.

Thanks,
Ruben

try
aptitude install libsnmp15