Sony Xperia TL "LT30a" (AT&T) on T-Mobile 4G LTE

Hi,

I have an unlocked AT&T Sony Xperia TL. It picks up T-Mobile 2G, 3G and LTE but can only establish connection to 2G & 3G 'No luck on LTE'.

* I'm in NYC market area.

Any ideas out there?

Phone specs:

http://www.gsmarena.com/sony_xperia_t_lte-5015.php