Add check if variable name is in reference labels

This will be important when variables that aren't in the ref case

lib/adf_dataset.py

@@ -344,16 +344,17 @@ def get_value_converters(self, case, variablename):
         res = self.adf.variable_defaults
         if variablename in res:
             vres = res[variablename]
-            if (case == self.ref_labels[variablename]) and (self.adf.compare_obs):
-                scale_factor = vres.get("obs_scale_factor",1)
-                add_offset = vres.get("obs_add_offset", 0)
-            else:
-                scale_factor = vres.get("scale_factor",1)
-                add_offset = vres.get("add_offset", 0)
+            if variablename in self.ref_labels:
+                if (case == self.ref_labels[variablename]) and (self.adf.compare_obs):
+                    scale_factor = vres.get("obs_scale_factor",1)
+                    add_offset = vres.get("obs_add_offset", 0)
+                else:
+                    scale_factor = vres.get("scale_factor",1)
+                    add_offset = vres.get("add_offset", 0)
         return add_offset, scale_factor
 
     #------------------
 
 
 
-
+