nope.. i want to know when you get this error, in what file, whats the include statement there or anything else that you think is relevant. obviously i have no clue what you're trying to do unless you tell me..rt? ..
i thought it was 'Testnamespaces.h' .. anyways is the path of the file available in your include path? -I option of the compiler? is this file actually present in the path, did you confirm? if you're using some IDE then you might have to check what's the include path set to.