date from datetimepicker tag is coming null

[linuspec]

<s:form action="Insert_Record_Rbt_in_DataBase">

<s:hidden value="%{tableName}" name="tableName"></s:hidden>

<s:textfield name="PLAN_NAME" label="planName"></s:textfield>
<s:textfield name="PLAN_CODE" label="planCode"></s:textfield>

<s:select name="PLAN_TYPE" label="planType" list="{1,2,3,4,5,6,7,8,9}" value="PLAN_TYPE" />

<s:select name="CIRCLE_ID" label="circleId" list="circle_id_list" value="circle_id_list" ></s:select>

<s:select name="INTERFACE" label="interface" list="{'C','X','J','I'}" value="PLAN_TYPE" />

<s:textfield name="VALIDITY" label="validity"></s:textfield>
<s:textfield name="PRICE" label="price"></s:textfield>
<s:textfield name="CONTENT_TYPE" label="contentType" ></s:textfield>

<s:datetimepicker name="START_TIME" id="date1" label="start time" displayFormat="yyyy-MM-dd" > </s:datetimepicker>
<s:datetimepicker name="END_TIME" id="date2" label="end time" displayFormat="yyyy-MM-dd" > </s:datetimepicker>

<s:select name="STATUS" label="status" list="{1,2,3,4}" ></s:select>
<s:select name="CHARGING_STATUS" label="chargingStatus" list="{1,2,3,4}"></s:select>

<s:textfield name="USER_DEF1" label="userDef1"></s:textfield>
<s:textfield name="SERVICE_ID" label="serviceId"></s:textfield>
<s:textfield name="SERVICE_TYPE" label="serviceType"></s:textfield>

<s:select name="SUBSCRIBER_TYPE" label="subscriberId" list="{'P','C'}"></s:select>

<s:textfield name="max_corp_user" label="max_corp_user"></s:textfield>

<s:submit type="button" name="InsertRecord" value="InsertRecord"></s:submit>
</s:form>