SummaryRow in p:dataTable not working - jsf

Question

I am trying to show a total value on my dataTable, my code is similar to the primefaces showcase DataTable - SummaryRow and still not working.
<p:dataTable id="dtCaixa" var="list" value="#{caixaMB.list}" paginator="true" rows="7"
paginatorPosition="bottom" rowsPerPageTemplate="10,15,20" liveScroll="true"
paginatorAlwaysVisible="false" emptyMessage="Nenhuma entrada!" liveResize="true">
<p:column headerText="Nome" sortBy="#{list.produtoFK.nome}" style="width:15%;">
<h:outputText value="#{list.produtoFK.nome}" />
</p:column>
<p:column headerText="Funcionário" sortBy="#{list.funcionarioFK.nome}">
<h:outputText value="#{list.funcionarioFK.nome}" />
</p:column>
<p:column headerText="Quantidade" sortBy="#{list.quantidade}">
<h:outputText value="#{list.quantidade}" />
</p:column>
<p:column headerText="Preço" >
<h:outputText value="#{list.produtoFK.preco}" rendered="#{not empty list.produtoFK}">
<f:convertNumber pattern="R$ #0.00" locale="pt_BR"/>
</h:outputText>
</p:column>
<p:column headerText="Total" sortBy="#{list.total}" >
<h:outputText value="#{list.total}" >
<f:convertNumber pattern="R$ #0.00" locale="pt_BR"/>
</h:outputText>
</p:column>
<p:column headerText="Remover" class="centered">
<p:commandButton icon="ui-icon-trash" title="excluir" onclick="PF('confirmaExclusao').show();">
<f:setPropertyActionListener target="#{caixaMB.itemSelecionado}" value="#{list}" />
</p:commandButton>
</p:column>
<p:summaryRow>
<p:column colspan="3" style="text-align:right">
<h:outputText value="Total:" />
</p:column>
<p:column>
<h:outputText value="#{caixaMB.total}">
</h:outputText>
</p:column>
</p:summaryRow>
</p:dataTable>
Does anybody have any idea why is this happening?

Answer 1

You need to sort the dataTable using at least one column if you want to use summaryRow. Check the Primefaces documentation.
E.g. put the attribute sortBy="#{myList.myOrderValue}" on the <p:datatable> tag.

Answer 2

I think what you're trying to achieve is the overall total of the column showing up at the bottom. I was caught out by the summaryRow function too, until I realised it was a grouping function and not a totalling summary. What I did you get around this was for the last column I added some footerText. You will have to calculate your totals manually (iterate over your dataset etc), then you can use something like:
<p:column style="text-align: right" footerText="$ #{invoicesbean.total}">
<f:facet name="header">
<h:outputText value="Amount" />
</f:facet>
........ etc
This worked well for me but YMMV!