Data strored in .RRD but nagios graph is not showingthe data

hi friends,

When I have dump the .rrd file it is showing the starting text like this. Does any one have any idea why the graph is empty.

The last value which I have updated was 100 and it is showing it properly in here. But the other entries around that time is showing as NAN.
One more information to share.

Instead of passing Max;Avg;Min;Cur value I am passing a single value to the database is that the issue?

Bcas I want the graph of single value or current value.

Will it work instead of passing values as 100. Shall I pass 0;0;0;100(Max;Avg;Min;Cur)

Pls help me if you have any idea.

<?xml version="1.0" encoding="utf-8"?> 0003
   <step> 300 </step> <!-- Seconds -->
   <lastupdate> 1227212391 </lastupdate> <!-- 2008-11-20 15:19:51 EST -->

   <ds>
          <name> pegcount </name>
          <type> GAUGE </type>
          <minimal_heartbeat> 600 </minimal_heartbeat>
          <min> NaN </min>
          <max> NaN </max>

          <!-- PDP Status -->
          <last_ds> 100 </last_ds>
          <value> 1.0000000000e+02 </value>
          <unknown_sec> 290 </unknown_sec>
   </ds>
          <cf> AVERAGE </cf>
          <pdp_per_row> 1 </pdp_per_row> <!-- 300 seconds -->

          <params>
          <xff> 5.0000000000e-01 </xff>
          </params>
          <cdp_prep>
                 <ds>
                 <primary_value> 0.0000000000e+00 </primary_value>
                 <secondary_value> 0.0000000000e+00 </secondary_value>
                 <value> NaN </value>
                 <unknown_datapoints> 0 </unknown_datapoints>
                 </ds>
          </cdp_prep>
          <database>
          <!-- 2008-11-18 14:55:00 EST / 1227038100 --> <row><v> NaN </v></row>
                 <!-- 2008-11-18 15:00:00 EST / 1227038400 --> <row><v> NaN </v></row>
                 <!-- 2008-11-18 15:05:00 EST / 1227038700 --> <row><v> NaN </v></row>
                 <!-- 2008-11-18 15:10:00 EST / 1227039000 --> <row><v> NaN </v></row>
                 <!-- 2008-11-18 15:15:00 EST / 1227039300 --> <row><v> NaN </v></row>
                 <!-- 2008-11-18 15:20:00 EST / 1227039600 --> <row><v> NaN </v></row>
                 <!-- 2008-11-18 15:25:00 EST / 1227039900 --> <row><v> NaN </v></row>
                 <!-- 2008-11-18 15:30:00 EST / 1227040200 --> <row><v> NaN </v></row>

Thanks
Novin