canvas - How to set the the zindex of datatemplate's in a longlistselector -

i have longlistselector images add in longlistselector. change margins of image make image go or down , on. want put image infront of image in longlistselector. have tried using canvas.zindex. have tried setting @ grid level, @ image level , @ top level of of longlistselector.() still doesn't work. have idea's? can find code bellow:

  <phone:longlistselector               x:name="southlonglistselector"              verticalalignment="bottom"             itemssource="{binding cards}"             canvas.zindex="{binding layer}"             selectionchanged="southlonglistselector_selectionchanged"                layoutmode="grid"             gridcellsize="50,200"              margin="0,0,0,-26"             >          <phone:longlistselector.itemtemplate >               <datatemplate>                 <grid                     background="transparent"                      margin="{binding gridoffset}"                     height="150"                     width="110"                                           >                     <!-- add image here-->                     <image                              source="{binding image}"                             >                     </image>                  </grid>              </datatemplate>         </phone:longlistselector.itemtemplate>                     </phone:longlistselector> 

thanks in advance,

i have used wpf xaml should same.

i don't see canvas referencing anywhere canvas.zindex. think want set panel of list canvas , set zindex times in list.

<phone:longlistselector.itemspanel>     <itemspaneltemplate>         <canvas/>     </itemspaneltemplate> </phone:longlistselector.itemspanel> <phone:longlistselector.itemtemplate >           <datatemplate>             <grid                 canvas.zindex"{binding layer}"                 background="transparent"                  margin="{binding gridoffset}"                 height="150"                 width="110"                                       >                 <!-- add image here-->                 <image                          source="{binding image}"                         >                 </image>              </grid>          </datatemplate>     </phone:longlistselector.itemtemplate>