another gui question-- using preview

I am trying to select the JPEG format in the export menu. I select export, but I can’t seem to choose JPEG

here is the code I am using:

tell application “System Events”
tell process “Preview”
set frontmost to true
tell menu bar 1
tell menu “File”
click menu item “Export?”
end tell
end tell

          -- below doesn't work 
             tell sheet 1  -- not sure about this, but taking it out doesnt do any good either 
                     tell menu "OtherViews" 
                             click menu item "JPEG" 
                     end tell 
             end tell 
     end tell 

end tell

here is what inspector is giving me for info:
<AXApplication: “Preview”>
<AXWindow: “Preview of “Microsoft Word - memorial.txt”.pdf”>

<AXMenu: “OtherViews”>
<AXMenuItem: ?JPEG?>

AXRole: “AXMenuItem”
AXRoleDescription: “menu item”
AXChildren: “(null)”
AXParent: “<AXMenu: “OtherViews”>”
AXTitle: “JPEG”
AXEnabled: “1”
AXPosition: “x=201 y=350”
AXSize: “x=159 y=19”
AXWidth: “159”
AXHeight: “19”
AXSelectedChildren: “(null)”
AXVisibleChildren: “(null)”
AXHelp: “(null)”
AXMenuItemCmdChar: “(null)”
AXMenuItemCmdVirtualKey: “(null)”
AXMenuItemCmdGlyph: “(null)”
AXMenuItemCmdModifiers: “(null)”
AXMenuItemMarkChar: “(null)”

please help

thank you for any help