Unable to share with Mac computer

[NOPdowop]

I think I have sharing set up properly, and I am able to share between two Windows 7 laptops with my user name and password. But when I try to share with a Mac computer, which uses the same user name and password, the Windows laptop claims my name or password are wrong, and the Mac also says the name and password are wrong for the Windows machine. But the same name and password work between the two Windows machines.