The defeat means the Millers are one place outside the relegation zone on goal difference only and face a huge match against Spalding Utd this week.
Carlton’s away form has been their saviour so far this year but they were unable to take anything back from a venue where they have regularly struggled over the years.
Manager Wayne Scott made four changes to the side which lost to Cleethorpes last time out. In came Niall Davie and Toby Moore, with debuts for Elie Ikwa and Karabo Motshweni. Out went James Frost, Harry Wood, Kyle Stovell and Aidan Austin.
There was the welcome return of Mamoke Akaunu on the bench.
Belper featured ex-Miller Danny Gordon (the Ilkeston one) and also had ex-Polish international Sebastian Malkowski in goal.
Belper started the sharper in blustery conditions and Danny South drew an early save from Jack Steggles.
George Milner then hit the bar after a free kick into the area.
Ryan Ebanks had to go off injured on just 13 minutes with Frost replacing him and within a minute the Nailers were ahead. A throw-in down the left saw a cross to the right where Alfred Thompson fired a left foot shot into the top corner.
As the half progressed Carlton found it almost impossible to keep any possession and it was Belper doing all the attacking.
Steggles made an excellent save from a Piteu Cruz effort on 41 minutes as the Millers tried to get to half time just a goal behind. They were unable to do so as Belper doubled their lead with a minute of the half remaining.
Malkowski hit it long to South who fed Crouz. He played the ball into Milner whose fierce shot saw Steggles get a hand to the ball but was unable to keep it out.
Scott brought on Stovell at half time and he had Carlton’s first real effort on goal, bringing a decent save from Malkowski on 55 minutes.
Akaunu came on with 30 minutes remaining as the final throw of the dice as Carlton tried desperately to fashion some chances.
Belper should have made it three shortly afterwards but Nathan Curtis fired over the bar after a cross from Crouz with the goal gaping.
Akaunu then fed Henry Rollinson who saw his shot go just over the top, before Motshweni hit an effort just wide.
Malkowski was equal to another Rollinson effort as the game seemed to be drifting to a home win but Carlton were handed a life line in the third minute of added time with a splendid goal.
Stovell slipped a great pass through to Aaron Opoku who ran clear of the defence before firing across Malkowski and into the net to the delight of the boisterous travelling support.
Cue some minor panic in the home defence as Carlton came forward from the kick off and earned a corner.
The ball found Moore unmarked at the back post but his header flew over the bar and with it went Carlton’s final hope of an unlikely equaliser.
Carlton Town: Steggles, Ebanks (Frost 13), Davie, Ikwa, Moore, Walker (Stovell 46), Rollinson, Bertram, Motshweni, Opoku Bartle (Akaunu 60). Unused substitutes: Podier, E Clarke
Goals: Opoku 90; Alfred Thompson 14, George Milner 44
Carlton Town Supporters Club MOTM: Riece Bertram
Attendance: 200
# | Team | Pl | Pts |
14. | Lincoln United | 38 | 43 |
15. | AFC Mansfield | 38 | 42 |
16. | Pickering Town | 38 | 35 |
17. | Wisbech Town | 38 | 31 |
18. | Spalding United | 38 | 31 |
19. | Carlton Town | 38 | 27 |
20. | Gresley FC | 38 | 25 |