diff --git a/RecipeGenerator.cs b/RecipeGenerator.cs
--- a/RecipeGenerator.cs
+++ b/RecipeGenerator.cs
@@ -246,7 +246,7 @@ namespace DesertPaintLab
                 for (; idx < costSortedReagents.Count; ++idx)
                 {
                     bool inUse = reagentInUse[idx];
-                    if (inUse == false)
+                    if ((inUse == false) && (costSortedReagents[(int)idx].Enabled))
                     {
                         //Console.WriteLine("Found free reagent idx {0}", idx);
                         reagentInUse[idx] = true;
@@ -384,7 +384,10 @@ namespace DesertPaintLab
                                         currentWeights[nextReagentPos] = weight;
                                         if (isInUse != 0)
                                         {
-                                            reagentInUse[reagentId] = true;
+                                            if (reagentId != INVALID_REAGENT)
+                                            {
+                                                reagentInUse[reagentId] = true;
+                                            }
                                         }
                                         ++nextReagentPos;
                                     }
@@ -540,10 +543,7 @@ namespace DesertPaintLab
             foreach (string name in ReagentManager.Names)
             {
                 Reagent reagent = ReagentManager.GetReagent(name);
-                if (reagent.Enabled)
-                {
-                    costSortedReagents.Add(reagent);
-                }
+                costSortedReagents.Add(reagent);
             }
             costSortedReagents.Sort(new ReagentCostSort());
         }
@@ -574,7 +574,7 @@ namespace DesertPaintLab
             recipe.Reactions = reactions;
             foreach (Reagent reagent in costSortedReagents)
             {
-                if (!reagent.IsCatalyst && reagent.RecipeMax >= 10)
+                if (!reagent.IsCatalyst && reagent.RecipeMax >= 10 && reagent.Enabled)
                 {
                     recipe.Clear();
                     recipe.AddReagent(reagent.Name, 10);
@@ -589,10 +589,13 @@ namespace DesertPaintLab
             }
             for (uint reagentIdx = 0; reagentIdx < costSortedReagents.Count; ++reagentIdx)
             {
-                SearchNode initialNode = new SearchNode(costSortedReagents, reagentIdx);
-                initialNode.MaxQuantity = maxQuantity;
-                initialNode.MaxReagents = maxReagents;
-                searchQueue.Enqueue(initialNode);
+                if (costSortedReagents[(int)reagentIdx].Enabled)
+                {
+                    SearchNode initialNode = new SearchNode(costSortedReagents, reagentIdx);
+                    initialNode.MaxQuantity = maxQuantity;
+                    initialNode.MaxReagents = maxReagents;
+                    searchQueue.Enqueue(initialNode);
+                }
             }
             
             // start worker threads to do the actual work