wrong values in RRD

I am using xymon 4.3.10.

My xymon client sends 2 values to the xymon server,

  disk_free = 10404175872
  disk_free_limit = 1000000000

The values displayed on the dashboard are correct.   But xymon server
stores a negative value for disk_free and zero for disk_free_limit.  How
can I make xymon stores the proper value to RRD?

    <ds>
        <name> diskfree </name>
        <type> DERIVE </type>
        <minimal_heartbeat> 600 </minimal_heartbeat>
        <min> NaN </min>
        <max> NaN </max>

        <!-- PDP Status -->
        <last_ds> 10404155392 </last_ds>
        <value> -6.7819016393e+04 </value>
        <unknown_sec> 0 </unknown_sec>
    </ds>

    <ds>
        <name> diskfreelimit </name>
        <type> DERIVE </type>
        <minimal_heartbeat> 600 </minimal_heartbeat>
        <min> NaN </min>
        <max> NaN </max>

        <!-- PDP Status -->
        <last_ds> 1000000000 </last_ds>
        <value> 0.0000000000e+00 </value>
        <unknown_sec> 0 </unknown_sec>
    </ds>


Thanks
P3