jsf primefaces download file in dilogue box is not working - jsf

Question

I want to download file in my jsf page, and below is my jsf page
<h:form id="MyListForm">
<p:commandButton value="Attachments" icon="ui-icon-transferthick-e-w" actionListener="#{myTeam.downloadImageDialogue}"
style="font-size: 10px;font-weight: bolder;vertical-align: text-bottom;width: 80px;" >
</p:commandButton>
</h:form>
and my bean code is:
public void downloadImageDialogue() {
RequestContext.getCurrentInstance().openDialog("AttachmentDialog");
}
and my dilogue xhtml page is:
<h:body>
<h:form>
<p:dataTable var="Attachment" value="#{attachmentDialogView.attachmentList}" rows="10">
<p:column headerText="File Name">
<h:outputText value="#{Attachment.fileName}" />
</p:column>
<p:column headerText="Download Attachment">
<p:commandLink ajax="false" id="dwldLink" action="#{attachmentDialogView.downloadImage}">
<f:setPropertyActionListener value="#{Attachment.id.itemId}" target="#{attachmentDialogView.imageItemId}" />
<f:setPropertyActionListener value="#{Attachment.fileName}" target="#{attachmentDialogView.fileName}" />
<f:setPropertyActionListener value="#{Attachment.id.callId}" target="#{attachmentDialogView.callID}" />
<p:graphicImage value="images/dnld1.png" width="25" height="25"/>
<p:fileDownload value="#{attachmentDialogView.file}"/>
</p:commandLink>
</p:column>
</p:dataTable>
</h:form>
</h:body>
and bean code is:
#ManagedBean(name = "attachmentDialogView")
#ViewScoped
public class AttachmentDialogView implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
private List<Attachment> attachmentList;
private String imageItemId;
private String fileName;
private DefaultStreamedContent file;
String callID;
#ManagedProperty("#{myTeamService}")
private MyTeamService service;
#PostConstruct
public void init() {
attachmentList = service.getAttachmentList(service.getCallId());
}
public void downloadImage() {
Session session = HibernateUtil.getSessionFactory().openSession();
Attachment attachment = null;
byte[] bImage;
ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();
try {
if (getCallID() == null || getCallID().equals("")) {
RequestContext.getCurrentInstance().execute("PF('check_dialog').show()");
} else {
attachment = (Attachment) session.createCriteria(Attachment.class).add(Restrictions.eq("id.itemId", getImageItemId())).add(Restrictions.eq("id.callId", getCallID())).uniqueResult();
bImage = attachment.getFileData();
InputStream stream = new ByteArrayInputStream(bImage);
file = new DefaultStreamedContent(stream,externalContext.getMimeType(getFileName()),getFileName());
}
} catch (Exception ex) {
ex.printStackTrace();
}finally {
session.close();
}
}
public List<Attachment> getAttachmentList() {
return attachmentList;
}
public void setAttachmentList(List<Attachment> attachmentList) {
this.attachmentList = attachmentList;
}
public MyTeamService getService() {
return service;
}
public void setService(MyTeamService service) {
this.service = service;
}
public String getImageItemId() {
return imageItemId;
}
public void setImageItemId(String imageItemId) {
this.imageItemId = imageItemId;
}
public String getFileName() {
return fileName;
}
public void setFileName(String fileName) {
this.fileName = fileName;
}
public DefaultStreamedContent getFile() {
return file;
}
public void setFile(DefaultStreamedContent file) {
this.file = file;
}
public String getCallID() {
return callID;
}
public void setCallID(String callID) {
this.callID = callID;
}
}
here dilogue opens correctly but image will not opened please help me.