How to save a registry key value to string

Using Microsoft's example of scrolling registry subkeys we have the following code:


        using (RegistryKey tempKey = test9999.OpenSubKey(subKeyName))
                {
      foreach (string valueName in tempKey.GetValueNames())
                {
              Console.WriteLine("{0,-8}: {1}", valueName,
              tempKey.GetValue(valueName).ToString());
        }

If the expression - tempKey.GetValue(valueName).ToString() - will write out to the console as a string why won't the following assignment work:

string SubValue = string.Empty;
...
...
SubValue  = tempKey.GetValue(valueName).ToString());

In debug mode, SubValue is assigned:  ""

If I evaluate the contents of 'valueName' by hovering over the variable during debug it shows the true value "My String Value"

Why would this be?

Thanks