MagSafe won't charge My mbp, but will charge others...

My MBP won't charge from its charger, so I brought it and the charger to the apple store. Met with a genius and they plugged it in and it worked, albeit only 90% of the time on my MBP. They tried it with their machines and it worked perfectly.

The genius sent me home with a brand new charger (which they tested with my MBP and theirs) that works and I get home: does not work at all.

Is this odd? I searched everywhere (google, macrumors, apple, here) to no avail. No one seems to have this problem.

The genius admitted that it may just be a freak incident,

Thoughts? Any help is appreciated. Thank you.