I need some help filtering on the custom property of a page.  I have seen a few posts where others are doing it, but it doesn't work for me.  Here is the code I am trying to get to work:

@helper MainNavAd(int menuItemID){
  var topNavAdsFolder = Library.NodeById(1268);

  <div class="subnav_content">
    this is my subnav content from the helper method: @menuItemID - 

    @*topNavPage is a Content Picker*@
    @topNavAdsFolder.Children.Where("topNavPage == @0", menuItemID).Count()
  </div>
}

This gives me the output of:
this is my subnav content from the helper method: 1059 - 0

But if i adjust the code to this:

@helper MainNavAd(int menuItemID){
  var topNavAdsFolder = Library.NodeById(1268);

  <div class="subnav_content">
    this is my subnav content from the helper method: @menuItemID - 

    @*topNavPage is a Content Picker*@
    @topNavAdsFolder.Children.First().GetPropertyValue("topNavPage")
  </div>
}

I get the follow:
this is my subnav content from the helper method: 1059 - 1059

So I feel like I am almost there.  Just can't figure out how to do the filtering without looping through all the children and using GetPropertyValue to compare the custom property.  

Any help would be appreciated.