Alternator problems

So, a few weeks back, my alternator indicator lights lit up. I
replaced my alternator, and replaced my battery, all was
good. A week later, my indicator lights come on again. I
pulled my alternator, tested it (tested good), put it back in,
and it was fine. Now, 2 weeks later, it comes on again. I am
at a loss as to what the problem is, can anyone help?