Index: /issm/trunk-jpl/src/m/classes/masstransport.m
===================================================================
--- /issm/trunk-jpl/src/m/classes/masstransport.m	(revision 24291)
+++ /issm/trunk-jpl/src/m/classes/masstransport.m	(revision 24292)
@@ -5,5 +5,5 @@
 
 classdef masstransport
-	properties (SetAccess=public) 
+	properties (SetAccess=public)
 		 spcthickness           = NaN;
 		 isfreesurface          = 0;
@@ -95,5 +95,7 @@
 			md = checkfield(md,'fieldname','masstransport.min_thickness','>',0);
 			md = checkfield(md,'fieldname','masstransport.requested_outputs','stringrow',1);
-
+			if ~any(isnan(md.stressbalance.vertex_pairing)),
+				md = checkfield(md,'fieldname','stressbalance.vertex_pairing','>',0);
+			end
 		end % }}}
 		function disp(self) % {{{
@@ -122,5 +124,5 @@
 			WriteData(fid,prefix,'object',self,'fieldname','vertex_pairing','format','DoubleMat','mattype',3);
 			WriteData(fid,prefix,'object',self,'fieldname','penalty_factor','format','Double');
-			
+
 			%process requested outputs
 			outputs = self.requested_outputs;
@@ -133,5 +135,5 @@
 		end % }}}
 		function savemodeljs(self,fid,modelname) % {{{
-		
+
 			writejs1Darray(fid,[modelname '.masstransport.spcthickness'],self.spcthickness);
 			writejsdouble(fid,[modelname '.masstransport.isfreesurface'],self.isfreesurface);
Index: /issm/trunk-jpl/src/m/classes/masstransport.py
===================================================================
--- /issm/trunk-jpl/src/m/classes/masstransport.py	(revision 24291)
+++ /issm/trunk-jpl/src/m/classes/masstransport.py	(revision 24292)
@@ -75,6 +75,6 @@
         md = checkfield(md, 'fieldname', 'masstransport.min_thickness', '>', 0)
         md = checkfield(md, 'fieldname', 'masstransport.requested_outputs', 'stringrow', 1)
-        if not np.any(np.isnan(self.vertex_pairing)):
-            md = checkfield(md, 'fieldname', 'masstransport.vertex_pairing', '>', 0)
+        if not np.any(np.isnan(self.vertex_pairing)) and len(self.vertex_pairing) > 0:
+            md = checkfield(md, 'fieldname', 'stressbalance.vertex_pairing', '>', 0)
 
         return md
Index: /issm/trunk-jpl/src/m/classes/stressbalance.m
===================================================================
--- /issm/trunk-jpl/src/m/classes/stressbalance.m	(revision 24291)
+++ /issm/trunk-jpl/src/m/classes/stressbalance.m	(revision 24292)
@@ -5,5 +5,5 @@
 
 classdef stressbalance
-	properties (SetAccess=public) 
+	properties (SetAccess=public)
 		spcvx                  = NaN;
 		spcvy                  = NaN;
@@ -57,5 +57,5 @@
 
 			 %Convergence criterion: absolute, relative and residual
-			 self.restol=10^-4; 
+			 self.restol=10^-4;
 			 self.reltol=0.01;
 			 self.abstol=10;
@@ -97,5 +97,7 @@
 			md = checkfield(md,'fieldname','stressbalance.loadingforce','size',[md.mesh.numberofvertices 3]);
 			md = checkfield(md,'fieldname','stressbalance.requested_outputs','stringrow',1);
-
+			if ~any(isnan(md.stressbalance.vertex_pairing)),
+				md = checkfield(md,'fieldname','stressbalance.vertex_pairing','>',0);
+			end
 			%singular solution
 			if ((~(any(~isnan(md.stressbalance.spcvx)) | any(~isnan(md.stressbalance.spcvy)))) & ~any(md.mask.groundedice_levelset>0)),
@@ -202,5 +204,5 @@
 		end % }}}
 		function savemodeljs(self,fid,modelname) % {{{
-		
+
 			writejs1Darray(fid,[modelname '.stressbalance.spcvx'],self.spcvx);
 			writejs1Darray(fid,[modelname '.stressbalance.spcvy'],self.spcvy);
Index: /issm/trunk-jpl/src/m/classes/stressbalance.py
===================================================================
--- /issm/trunk-jpl/src/m/classes/stressbalance.py	(revision 24291)
+++ /issm/trunk-jpl/src/m/classes/stressbalance.py	(revision 24292)
@@ -134,5 +134,5 @@
         md = checkfield(md, 'fieldname', 'stressbalance.loadingforce', 'size', [md.mesh.numberofvertices, 3])
         md = checkfield(md, 'fieldname', 'stressbalance.requested_outputs', 'stringrow', 1)
-        if not np.any(np.isnan(self.vertex_pairing)) and len(self.vertex_pairing)>0:
+        if not np.any(np.isnan(self.vertex_pairing)) and len(self.vertex_pairing) > 0:
             md = checkfield(md, 'fieldname', 'stressbalance.vertex_pairing', '>', 0)
         #singular solution