diff --git a/NBi.Testing/Acceptance/GenbiL/ConcatenateSplitGroup.cs b/NBi.Testing/Acceptance/GenbiL/ConcatenateSplitGroupTest.cs
similarity index 78%
rename from NBi.Testing/Acceptance/GenbiL/ConcatenateSplitGroup.cs
rename to NBi.Testing/Acceptance/GenbiL/ConcatenateSplitGroupTest.cs
index 53d674b85..99c2d54aa 100644
--- a/NBi.Testing/Acceptance/GenbiL/ConcatenateSplitGroup.cs
+++ b/NBi.Testing/Acceptance/GenbiL/ConcatenateSplitGroupTest.cs
@@ -34,9 +34,6 @@ public void SetupTest()
         {
             if (File.Exists(TargetFilename))
                 File.Delete(TargetFilename);
-
-            //if(File.Exists(CsvFilename))
-            //    File.Delete(CsvFilename);
         }
 
         //Called after each test
@@ -49,13 +46,17 @@ public void TearDownTest()
         #endregion
 
         [Test]
-        public void Execute_Group_FileGenerated()
+        public void Execute_Group_FileGeneratedWithoutListString()
         {
             var generator = new TestSuiteGenerator();
             generator.Load(DefinitionFilename);
             generator.Execute();
 
             Assert.That(File.Exists(TargetFilename));
+            var text = File.ReadAllText(TargetFilename);
+            Assert.That(text, Is.Not.StringContaining("System.Collections.Generic.List`1[System.String]"));
+            Assert.That(text, Is.StringContaining("<category>91675</category>"));
+            Assert.That(text, Is.StringContaining("<category>75755</category>"));
         }
 
 
diff --git a/NBi.Testing/NBi.Testing.csproj b/NBi.Testing/NBi.Testing.csproj
index 05c88b93f..17f597972 100644
--- a/NBi.Testing/NBi.Testing.csproj
+++ b/NBi.Testing/NBi.Testing.csproj
@@ -85,7 +85,7 @@
     <Compile Include="..\AssemblyInfo.cs">
       <Link>Properties\AssemblyInfo.cs</Link>
     </Compile>
-    <Compile Include="Acceptance\GenbiL\ConcatenateSplitGroup.cs" />
+    <Compile Include="Acceptance\GenbiL\ConcatenateSplitGroupTest.cs" />
     <Compile Include="Acceptance\GenbiL\GroupTest.cs" />
     <Compile Include="Acceptance\GenbiL\CommentTest.cs" />
     <Compile Include="Acceptance\GenbiL\GroupReduceTest.cs" />
diff --git a/NBi.genbiL/Action/Case/GroupCaseAction.cs b/NBi.genbiL/Action/Case/GroupCaseAction.cs
index ee431a421..cd7ac023d 100644
--- a/NBi.genbiL/Action/Case/GroupCaseAction.cs
+++ b/NBi.genbiL/Action/Case/GroupCaseAction.cs
@@ -47,8 +47,11 @@ public void Execute(GenerationState state)
                     if (dataTable.Rows[firstRow][columnListId] == DBNull.Value)
                         dataTable.Rows[firstRow][columnListId] = new List<string>();
 
-                    var list = dataTable.Rows[firstRow][columnListId] as IList<string>;
-                    list.Add(dataTable.Rows[i][columnId].ToString());
+                    var list = dataTable.Rows[firstRow][columnListId] as List<string>;
+                    if (dataTable.Rows[i][columnId] is IEnumerable<string>)
+                        list.AddRange(dataTable.Rows[i][columnId] as IEnumerable<string>);
+                    else
+                        list.Add(dataTable.Rows[i][columnId].ToString());
                 }
 
                 if (isIdentical && i != 0)