API Time Entry Additional Fields

Hi,
I added a custom field and all is good and well when I use the APi
to get the time Entries and the field gets retrurned.

<response uri="/api/xml/getTimeEntryDetails">
<result>
    <status>Success</status>
    <statuscode>200</statuscode>
    <total>
      <form name="totalCost">0.0</form>
      <form name="totalMinutesTakenToResolve">30</form>
      <form name="totalHoursTakenToResolve">3</form>
    </total>
    <timeEntries>
      <timeentry>
        <form name="minutesTakenToResolve">30</form>
        <form name="rateType" />
        <form name="hoursTakenToResolve">1</form>
        <form name="additionalCost">0.0</form>
        <form name="timeEntryType" />
        <form name="cost">0.0</form>
        <form name="supportrep">Þorvaldur Hafdal</form>
        <form name="SupportRepCostperhour">0.0</form>
        <form name="timeEntryID">36902</form>
        <form name="createdBy">Þorvaldur Hafdal</form>
        <form name="description">Just wanna</form>
        <form name="executedTime">15-04-03 21:24:49</form>
        <form name="Reference">EFG</form>
        <form name="chargeType">Billable</form>
      </timeentry>
      <timeentry>
        <form name="minutesTakenToResolve">00</form>
        <form name="rateType" />
        <form name="hoursTakenToResolve">2</form>
        <form name="additionalCost">0.0</form>
        <form name="timeEntryType" />
        <form name="cost">0.0</form>
        <form name="supportrep">Þorvaldur Hafdal</form>
        <form name="SupportRepCostperhour">0.0</form>
        <form name="timeEntryID">36901</form>
        <form name="createdBy">Þorvaldur Hafdal</form>
        <form name="description">Work seting up a proxy server</form>
        <form name="executedTime">15-04-03 20:38:44</form>
        <form name="Reference">ABCD</form>
        <form name="chargeType">Billable</form>
      </timeentry>
    </timeEntries>
</result>
</response>

I am unable to update the the field value using the API.(Reference)

Is it not possible using the API ?

?apikey=<apikey>&description=Just%20wanna&workHours=1&workMinutes=30&supportRep=%C3%9Eorvaldur%20Hafdal&executedTime=15-04-03%2021%3A24%3A49&time-format=yy-MM-dd%20HH%3Amm%3Ass&cost=0&additionalCost=0&Reference=26000&billingStatus=billable&vLinkID=0f971251-371c-4af4-9204-6e572458583a

Best regards,
Valdi Hafdal
URL : http://www.vlink.is

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