Why this code not working???

I am trying to save a mesh in assets. But it is not working.

I am making an editor window. Here is a test code:

		if (GUILayout.Button ("Try Save")) {
			AssetDatabase.AddObjectToAsset (new Mesh(),"Assets/text_M.asset");
			AssetDatabase.Refresh ();

When I clicked “Try Save” button… nothing happened. object is not saved… Why???

I am using Unity 5 Personal Edition.

Are you trying to save the mesh as an asset (AssetDatabase.CreateAsset) or trying to add the mesh to an existing asset?
Do you call AssetDatabase.SaveAssets at some point?