diff --git a/panoconfig.py b/panoconfig.py
index ace163e..01c8aae 100644
--- a/panoconfig.py
+++ b/panoconfig.py
@@ -90,6 +90,7 @@ for iline1,line1 in enumerate(linesinput):
             if (targetYaw2=='i'):
                 targetYaw2=0
                 for iline3,line3 in enumerate(linesinput):
+                    assert len(line3.split(','))==5, "not enough values in line "+str(iline3+1)+" : "+str(line3.split(','))
                     fromID3,toID3,pitch3,yaw3,targetYaw3=line3.split(',')
                     if (toID2==fromID3 and fromID2==toID3):
                         targetYaw2=int(yaw3)-180