Invisibility, line of effect, concentration spells

[Avenger]

Situation at hand: the target of a 'Target: creature(s) / Duration: concentration(+x rnd)' spell becomes invisible. (e.g. spells like Id Insinuation)
I'm assuming the spell effect ends on that target the next round via breaking the aiming a spell rule/line of effect.
Or the caster can still concentrate on the spell to maintain the effect even tho he can't see/pinpoint the target?

[Speaker for the Dead]

Am I looking at the right spell? It says the target becomes confused, not invisible?

[Bob Bob Bob]

Concentration wrote:

The spell lasts as long as you concentrate on it. Concentrating to maintain a spell is a standard action that does not provoke attacks of opportunity. Anything that could break your concentration when casting a spell can also break your concentration while you're maintaining one, causing the spell to end. See concentration.

You can't cast a spell while concentrating on another one. Some spells last for a short time after you cease concentrating.

A duration of "concentration" has no requirement other than spending a standard action and making a concentration check if necessary.

[Avenger]

Speaker for the Dead wrote:

Am I looking at the right spell? It says the target becomes confused, not invisible?

The target rolls 'act normally', then casts invisibility on itself or an ally makes the target invisible

[Avenger]

Bob Bob Bob wrote:

A duration of "concentration" has no requirement other than spending a standard action and making a concentration check if necessary.

I guess what I'm basically asking is if the effect of the concentration spell stops if the requirements for targeting the spell are not met in any subsequent round.

[Chemlak]

No. The spell lasts as long as the caster concentrates +1 round, regardless of whether the target is now a viable subject to target with the spell, with one exception that I can find: if the target moves out of range, the confusion effect is suspended.