SC2: Why can't I build a tech lab?

[Bottomsup]

sorry for the n00b question, but i really like this game and am new to RTS so I'm trying to get up to speed.

See the below screenshot where I have plenty of minerals, gas, supply depots, and no units building, but can not add a tech lab to build ghosts?

TIA

http://img249.imageshack.us/img249/6348/sc220101229234237775.jpg

[jazon1]

i haven't played in a bit but in the pic it looks like you already had a different lab attached to that barracks.

[Dracknem]

You can only have one lab attached to a building. As jazon1 already pointed out, you have a reactor attached to that barracks.

In order to build a tech lab, lift the barracks up (the up-arrow symbol on your screen) and then you can choose tech lab and land the barracks in a new location.

[bigben6]

Think of it like the add on in SC 1, you could have a nuke silo OR make BC's, in SC2 you can have a Reactor OR tech lab, anyways SC2 requires at least 3 barracks if your going ground based soalof of people do 4 rax with 1 reactor 2 tech labs... just FYI

[Marshmallow64]

Yea its cause you already have a reactor on the barrack, gotta lift it up, then build a tech lab.

[Bottomsup]

Thx