jsf validator bean values in parameter lost

Question

            <h:dataTable value="#{products.getAllProducts()}"
                         var="product">
                ....

                <h:column rendered="...">
                    <f:facet name="header">Quantity</f:facet>
                    <h:inputText id="basket-qty" value="#{basket.qty}" rendered="#{product.stock.qty > 0}" >
                        <f:convertNumber integerOnly="true" />
                        <f:validateLongRange minimum="1" maximum="#{product.stock.qty}" />
                    </h:inputText>
                    <h:message id="textmessage" for="basket-qty" />
                </h:column>

                <h:column rendered="...">
                    <h:commandButton action="#{basket.addProduct(product)}"
                                     value ="Add to Basket">
                    </h:commandButton>
                </h:column>

            </h:dataTable>

Basically the problem is that maximum="#{product.stock.qty}" is evaluating to zero, therefore my range is 0-0?

product.stock.qty evaluates correctly elsewhere in the table.