diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Uns/UnsTreeServiceVirtualTagTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Uns/UnsTreeServiceVirtualTagTests.cs
index d7fafe1c..dfb2399e 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Uns/UnsTreeServiceVirtualTagTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Uns/UnsTreeServiceVirtualTagTests.cs
@@ -163,6 +163,24 @@ public sealed class UnsTreeServiceVirtualTagTests
         result.Error.ShouldBe("A virtual tag named 'computed' already exists on this equipment.");
     }
 
+    /// <summary>Creating a virtual tag with no script chosen is blocked.</summary>
+    [Fact]
+    public async Task CreateVirtualTag_no_script_blocked()
+    {
+        var (service, dbName) = Fresh();
+        SeedEquipmentAndScript(dbName);
+
+        var input = Input("VTAG-1", "computed", scriptId: "", changeTriggered: true);
+        var result = await service.CreateVirtualTagAsync("EQ-1", input);
+
+        result.Ok.ShouldBeFalse();
+        result.Error.ShouldNotBeNull();
+        result.Error.ShouldContain("Pick a script");
+
+        using var db = UnsTreeTestDb.CreateNamed(dbName);
+        db.VirtualTags.Any(v => v.VirtualTagId == "VTAG-1").ShouldBeFalse();
+    }
+
     // ----- UpdateVirtualTag -----
 
     /// <summary>Updating a virtual tag changes its mutable fields and keeps EquipmentId.</summary>
@@ -211,6 +229,29 @@ public sealed class UnsTreeServiceVirtualTagTests
         result.Error.ShouldBe("Row no longer exists.");
     }
 
+    /// <summary>Renaming a virtual tag to a name already used by another tag on the same equipment is blocked.</summary>
+    [Fact]
+    public async Task UpdateVirtualTag_duplicate_name_on_equipment_blocked()
+    {
+        var (service, dbName) = Fresh();
+        SeedEquipmentAndScript(dbName);
+        await service.CreateVirtualTagAsync("EQ-1", Input("VTAG-A", "vt_a"));
+        await service.CreateVirtualTagAsync("EQ-1", Input("VTAG-B", "vt_b"));
+
+        byte[] rv;
+        using (var db = UnsTreeTestDb.CreateNamed(dbName))
+        {
+            rv = db.VirtualTags.Single(v => v.VirtualTagId == "VTAG-A").RowVersion;
+        }
+
+        var input = Input("VTAG-A", "vt_b"); // try to rename to the name already used by VTAG-B
+        var result = await service.UpdateVirtualTagAsync("VTAG-A", input, rv);
+
+        result.Ok.ShouldBeFalse();
+        result.Error.ShouldNotBeNull();
+        result.Error.ShouldContain("already exists on this equipment");
+    }
+
     // ----- DeleteVirtualTag -----
 
     /// <summary>Deleting a virtual tag removes the row.</summary>