How to properly upload files - primefaces

Question

I have a problem with file upload. I have a page, where there is an output box. And if I need to make more then 1 mP (myProduct for example) and I add the same section all look OK. But when I fill first mP and add next, the file uploaded in first section in not OK. If I choose file in first section, and click to upload, get error "The file was not choosed"....Some tips how to solve it? btw: sorry for my english
<div class="ShadowBox whiteback RedBorderedBox ui-fluid">
<div class="CI">
<p:outputPanel styleClass="C100">
<h1 class="BT">#{msg.mP}</h1>
<div class="C100">
<p:dataList id="#{id}_mPList"
value="#{mPs}" var="rec"
type="definition" emptyMessage="No data">
<p:panelGrid columns="8" layout="grid"
style="border:0px !important; background:none;"
styleClass="ui-panelgrid-blank"
columnClasses="ui-grid-col-5, ui-grid-col-5">
<p:inputTextarea placeholder="#{msg.mPPro}"
value="#{rec.p}" disabled="#{MyBean.locked}"
rows="1">
<p:ajax listener="#{MyBean.inv()}" update="#(.buttonPanelClass)"
event="change"/>
</p:inputTextarea>
<p:fileUpload value="#{MyBean.modFile}" mode="simple" skinSimple="true" label="Choose file"
update="#{id}_mPList #(.buttonPanelClass)" />
<p:commandButton value="Upload" action="#{MyBean.saveModFile(rec, modCat)}" ajax="false"
update="#{id}_mPList #(.buttonPanelClass)" icon="fa fa-arrow-up green"/>
</p:panelGrid>
<f:facet name="footer">
<p:commandButton immediate="true"
update="#{id}_mPList #(.buttonPanelClass)"
action="#{MyBean.addMedProduct(medProducts)}"
value="#{msg.add}"
disabled="#{MyBean.locked}"/>
</f:facet>
</p:dataList>
</div>
</p:outputPanel>
</div>
</div>
</p:outputPanel>