Index: AppEnv.cs
===================================================================
--- AppEnv.cs   (revision 6312)
+++ AppEnv.cs   (working copy)
@@ -569,7 +569,11 @@
         public string GenerateTerrainConfig()
         {
             MessageLine(" -------- Build terrain config -------- ");
-            terrainConfigObj.GenerateExpandedTask();
+            if (!terrainConfigObj.GenerateExpandedTask())
+            {
+                RunError("Failed build terrain config");
+                return null;
+            }
             if (!terrainConfigObj.Run(this, true, true))
             {
                 RunError("Failed build terrain config");
Index: Operations/TerrainConfig.cs
===================================================================
--- Operations/TerrainConfig.cs (revision 6312)
+++ Operations/TerrainConfig.cs (working copy)
@@ -283,6 +283,8 @@
             ValidationResult = true;
             ValidateOnNullAndEmptyString("TERRAIN_CONFIG_DIR",
                                          "terrain config output directory isn't specified.", appEnv);
+            if (!ValidationResult)
+                return false;
             ValidateOnNullAndEmptyString("GEOTIFF",
                                          "elevation data (geotif) file isn't specified.", appEnv);
             ValidateOnNullAndEmptyString("DEFMATERIAL",
@@ -289,7 +291,8 @@
                                          "defmaterial isn't specified.", appEnv);
             ValidateOnNullAndEmptyString("IMAGE",
                                          "image file isn't specified.", appEnv);
-            return ValidationResult;
+            return true;
+            //return ValidationResult;
         }

         private void InitVariables()