Poller.php returns values but rrd file is 'nan'

[LBird2115]

Hello,

I'm really hoping someone can help me with a problem I am having. I have a new installation of Cacti, and I am using the default Interface Statistics data source.
ALL my graphs including localhost data have no values, they are all 'nan', however I see data is returned successfully in the log. Permissions of the rrd folder are all set correctly and when I delete the .rrd files they are re-created correctly.

Any ideas?

6/06/2015 04:24:02 PM - SYSTEM STATS: Time:0.5390 Method:cmd.php Processes:15 Threads:N/A Hosts:4 HostsPerProcess:1 DataSources:3 RRDsProcessed:2
06/06/2015 04:24:02 PM - POLLER: Poller[0] CACTI2RRD: /bin/rrdtool update /data/web/webapp_cacti/public_html/rra/3/10.rrd --template traffic_in:traffic_out 1433604242:4157725268:2640357073
06/06/2015 04:24:02 PM - CMDPHP: Poller[0] Time: 0.2184 s, Theads: N/A, Hosts: 1
06/06/2015 04:24:02 PM - CMDPHP: Poller[0] Host[3] DS[10] SNMP: v3:[...], dsname: traffic_out, oid: .1.3.6.1.2.1.2.2.1.16.11103, output: 2640357073
06/06/2015 04:24:02 PM - CMDPHP: Poller[0] Host[3] DS[10] SNMP: v3: [...], dsname: traffic_in, oid: .1.3.6.1.2.1.2.2.1.10.11103, output: 4157725268

# rrdtool fetch 10.rrd AVERAGE | tail -20
1433602500: -nan -nan
1433602800: -nan -nan
1433603100: -nan -nan
1433603400: -nan -nan
1433603700: -nan -nan
1433604000: -nan -nan
1433604300: -nan -nan
1433604600: -nan -nan
1433604900: -nan -nan
1433605200: -nan -nan
1433605500: -nan -nan
1433605800: -nan -nan
1433606100: -nan -nan
1433606400: -nan -nan
1433606700: -nan -nan
1433607000: -nan -nan
1433607300: -nan -nan
1433607600: -nan -nan
1433607900: -nan -nan
1433608200: -nan -nan