Luton dominated for long periods but couldn't find a way past the massed ranks of defenders.
Luton started well and went close five minutes in when David Bell's teasing left-foot cross from the right threatened to deceive Kieren Westwood and creep in at the far post only to travel just wide of the upright.
Bell was involved again nine minutes later as he latched on to Calvin Andrew's nod down and teed up Darren Currie to send in a cross-shot from 12 yards that was cleared away by Peter Murphy's last-ditch challenge.
Bell then really should have given the Hatters the lead in the 15th minute after Currie's corner caused mayhem in the visitors' box.
Chris Coyne's initial header from the flag-kick was well blocked by Westwood and, as the ball dropped, Bell somehow struck the underside of the bar from two yards before the Carlisle number eventually claimed.
The Cumbrians created their first real opening 20 minutes in when Marc Bridge-Wilkinson found Danny Graham, who teed up Simon Hackney to cross from the left for Joe Garner, whose 12-yard header was well tipped over by Dean Brill.
Another slick Carlisle move three minutes later ended with Kevin Gall's driving run finding Graham, who laid off for Bridge-Wilkinson to drill a low 20-yarder just past the post.
Luton though again should have scored in the 25th minute when Andrew powered into the penalty area and dinked the ball past Westwood into the path of Currie, but the former Ipswich man's shot was blocked by David Raven when it seemed much easier to score.
After a lull in the action it was the hosts who threatened again in the 37th minute when another Andrew flick was seized upon by Dave Edwards, who hit an instant 30-yard, right-foot volley that flew narrowly wide.
But in injury time it was the visitors who almost took the lead when Jaroslaw Fojut fouled Gall on the edge of the area and Dean Brill had to uncomfortably smuggle away Murphy's low curling free-kick.
Bell let rip with a cracker himself in the 57th minute as he controlled Matthew Spring's cross-field pass, cut inside Zigor Aranalde and saw his left-foot 25-yard shot punched away by Westwood.
Westwood was in action again on the hour mark as he leaped to push Andrew's looping shot over the bar after the striker had turned Danny Livesey in the penalty area.
The Carlisle keeper then touched Coyne's far-post header round the post in the 67th minute before his side created their first opening of the half a minute later as Graham stung the hands of Brill with a 25-yard drive.
Graham went close again in the 77th minute as the ball flew off his thigh from close in after Joe Garner's header, but Brill was on hand to save.
Graham then almost hit a winner in the final minute as Raven's marauding run from the back set the striker up for a shot on goal 16 yards out, but the ball flew past the far post.