Graphs shows no data

Hi,

I am using RHEL 6 linux based os.

Specificiation :
Observium v0.14.4.5229
mysql Ver 14.14 Distrib 5.1.71
Php 5.3
net-snmp-5.5

Configured observium successfully with help of observium.org tutorial.
Every graph is drawn and it's showing value as “-nan” for each data point and devices.
Graph showing no data and nan.

Discover.php appears to be running fine and collecting data :
MySQL: Cell[2/0s] Row[125/0.03s] Rows[66/0.02s] Column[0/0s] Update[45/1.2s] Insert[22/0.16s] Delete[0/0s]

poller.php appears to be running fine and collecting data :
UPDATED!
MySQL: Cell[0/0s] Row[20/0.01s] Rows[78/0.02s] Column[0/0s] Update[58/0.12s] Insert[4/0.17s] Delete[0/0s]

Thanks in advance.