Index: src/Deltares.DSoilModel.Forms/DSoilModelPlugin.cs
===================================================================
diff -u -r417 -r418
--- src/Deltares.DSoilModel.Forms/DSoilModelPlugin.cs	(.../DSoilModelPlugin.cs)	(revision 417)
+++ src/Deltares.DSoilModel.Forms/DSoilModelPlugin.cs	(.../DSoilModelPlugin.cs)	(revision 418)
@@ -1084,6 +1084,11 @@
             // Cannot delete {0} [{1}] because it's used in {2} [{3}]"
             var msg = string.Format(formattedErrorStr, objToDelete.Name, objToDelete.GetType().Name, objUses.Name, objUses.GetType().Name);
             LogManager.Add(new LogMessage(LogMessageType.Error, objUses, msg));
+
+            if (!FormsSupport.IsTreeVisible(mainForm.DynamicOutputControl))
+            {
+                FormsSupport.MakeTreeVisible(mainForm.DynamicOutputControl);
+            }
         }
 
         private bool CanDelete(object o)