Extract month number from Date field in view entity

[makreza]

I have a view entity. And I have a column which is shipmentDate. From this column I want to create a new column shipmentMonthNo by extracting the shipmentDate. There is an entity function named extract-month. I used it but not working.

<view-entity entity-name="MerShipmentSchedule" package-name="org.ofbiz.party.party" title="Party Relationship And Details">
    <member-entity entity-alias="MOB" entity-name="MerOrderBook"/>
    <member-entity entity-alias="PER" entity-name="Pers"/>
    <member-entity entity-alias="PTYGRP" entity-name="PartyGrp"/>
    <alias-all entity-alias="MOB"/>
    <alias name="shipmentMonthNo" entity-alias="MOB"  field="shipmentDate" function="extract-month" ></alias>
    <alias entity-alias="PER" name="nickname"/>
    <alias entity-alias="PTYGRP" name="groupName"/>
    <view-link entity-alias="MOB" rel-entity-alias="PER" rel-optional="true">
        <key-map field-name="merchandiserId" rel-field-name="partyId"/>
    </view-link>
    <view-link entity-alias="MOB" rel-entity-alias="PTYGRP" rel-optional="true">
        <key-map field-name="buyerId" rel-field-name="partyId"/>
    </view-link>
</view-entity>