The codemetric displays CyclomaticComplexity/LineOfCodes always 0 if the checked library contains an enumeration with calculated CC/LoC = 0 (there are multiple lines of code in the enumeration), see attached image vsCodeMetrics_1.png.

CodeMetrics calculation result in VS2010 shows the same values for the ExampleEnum, but the CC/LoC at upper levels shows a value != 0, see image vsMetrics_1.png.

Level 1: checked .dll
Level 2: namespace
Level 3: classes/enums

Example Enum:
/// <summary>...</summary>
public enum ExampleEnum