diff --git a/netcore/create_modules.py b/netcore/create_modules.py
index f4225a6..df67c48 100644
--- a/netcore/create_modules.py
+++ b/netcore/create_modules.py
@@ -125,6 +125,9 @@ def change_range(weights,NewMin=1,NewMax=100):
 	OldMin = min(weights)
 	OldRange = (OldMax - OldMin)  
 	NewRange = (NewMax - NewMin)
+	if OldRange==0:
+		# there is only one value for the seed weights
+		OldRange=NewRange
 	sizes = [0]*len(weights)
 	for i,w in enumerate(weights):   
 		NewValue = (((w - OldMin) * NewRange) / OldRange) + NewMin