GoTo not holding value

I am trying to pass a value of InventoryNum in a URL link, but for some reason the value is not working. Here is my code

<div class="col-12 col-md-4" dmx-repeat:new-inventory="serverconnect1.data.new_inventory.data">
    <img alt="image" class="img-fluid rounded-top" dmx-bind:src="'http://vanderbundtcollection.com/carimages/'+photoURL1" dmx-on:click="browser1.goto('inventory_details.html?inventorynum='+InventoryNum)">
    <p class="text-center bg-info text-light pt-2 pb-2">
         {{Year+'&nbsp;'+Make+'&nbsp;'+Model}}
    </p>

The InventoryNum is blank, but the Year / Make / Model is fine.

Any ideas why the InventoryNum is not working?
When i click on the link that is on the website it comes up like this

/inventory_details.html?inventorynum=