face, where I applied concealer? Since concealer is meant for dark spot on the face, how can I apply concealer and at the same time the colour looks even with the foundation on my face?

because it is oily..
even tho it dosn't look like it

Same as Katters above! =)

because that even though you can't see them in light, concealer puts shadows of its own on your face. Just make sure you don't take pics in dark rooms . problem solved.

You may be using a concealer in a shade that appears too light in the flash. Try using a darker shade if you expect to be photographed in the dark with the flash on. I'm sure that in normal light, it looks natural, but the flash is such a sudden and harsh light so it distorts the color on your face.
Or you can use makeup made for television, like MAC, which has fuller coverage and is a little thicker so you don't get that discoloration or washed out face in the harsh light.