true/false not usable in set var, use string value

includes/digital_resources.inc

 {% if models.dzi | length > 0 %}
-	{% set dzi_enabled = true %}
-{% else %}
-	{% set dzi_enabled = false %} 
+	{% set dzi_enabled = 'true' %}
+	{% set dzi_dr = 'true' %}
+	
 {% endif %}
 {% if models.digitalresources | length > 0 %}
-  {% set dr_enabled = true %}
-{% else %}
-  {% set dr_enabled = false %}
+  {% set dr_enabled = 'true' %}
+  {% set dzi_dr = 'true' %}
 {% endif %}
-      {% if dzi_enabled %}
+      {% if dzi_enabled == 'true' %}
       <!-- Contains the OpenSeadragon viewer -->
       <div class="ui top attached tab segment no-padding active" data-tab="dzi"> 
         <div id="dzi1" style="height:50rem; background-color: black;"></div>
@@ -16,7 +15,7 @@
       {% endif %}   
 
       {% if models.digitalresources| length > 0 %}
-      <div data-tab="jpeg" class="{% if not dzi_enabled %}active{% endif %} ui top attached tab segment no-padding">
+      <div data-tab="jpeg" class="{% if not dzi_enabled == 'true' %}active{% endif %} ui top attached tab segment no-padding">
 
         <!-- fotorama.css & fotorama.js. -->
         <link  href="https://cdnjs.cloudflare.com/ajax/libs/fotorama/4.6.3/fotorama.css" rel="stylesheet">
@@ -31,10 +30,10 @@
       </div>
       {% endif %}
       
-          {% if dzi_enabled &&  dr_enabled %}
+          {% if dzi_enabled == 'true' &&  dr_enabled == 'true' %}
     <div class="ui bottom attached tabular menu dr-tab">
-      <a class="item {% if dzi_enabled %}active{% else %}disabled{% endif %}" data-tab="dzi">Zoom</a>
-      <a class="item {% if not dzi_enabled %}active{% endif %}" data-tab="jpeg">Jpeg</a>
+      <a class="item {% if dzi_enabled == 'true' %}active{% else %}disabled{% endif %}" data-tab="dzi">Zoom</a>
+      <a class="item {% if not dzi_enabled == 'true' %}active{% endif %}" data-tab="jpeg">Jpeg</a>
     
     
     <div id="dzi-control" class="right menu">