data Table sorting is not working

[bphalak]

See below code. sorting is not working in my code please check.

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<p:dataTable id="grid" var="user" value="#{EmpBean.employeeList}" style="width: 800px;" >
<f:facet name="header">
<h:outputText value="#{msgs.LBL_0054}"/>
</f:facet>
<p:column sortBy="#{user.employeeNumber}" styleClass="noColomn">
<f:facet name="header">
<h:outputText value="#{msgs.LBL_0044}" />
</f:facet>
<h:outputText value="#{user.employeeNumber}"/>
</p:column>
<p:column sortBy="#{user.name}" >
<f:facet name="header">
<h:outputText value="#{msgs.LBL_0045}" />
</f:facet>
<h:outputText value="#{user.name}"/>

</p:column>
<p:column sortBy="#{user.email}" >
<f:facet name="header">
<h:outputText value="#{msgs.LBL_0046}" />
</f:facet>
<h:outputText value="#{user.email}"/>

</p:column>
<p:column sortBy="#{user.email}" >
<f:facet name="header">
<h:outputText value="#{msgs.LBL_0047}" />
</f:facet>
<h:outputText value="#{user.email}"/>
</p:column>
</p:dataTable>