Bent, who has been named on the bench in four of Villa's last five encounters, missed out again in Tuesday night's Capital One Cup win at Swindon.
Youngster Andreas Weimann was named ahead of the 28-year-old England international, while Lambert's preferred striking duo this season Christian Benteke and Gabby Agbonlahor both got on the scoresheet.
The manager insists Bent's exclusion came down to tactics and it remains to be seen if he will feature against his old club Sunderland on Saturday.
Asked if there is a problem between himself and Bent, Lambert told the Daily Mirror: "No, nothing. Not a thing - I speak to him.
"All I try and do is pick a team which will win a game. Everybody is involved in it and that is all I do.
"The system at Swindon dictated I played Andi [Weimann] out wide. To be fair to Andi, I think he has been playing really well and been unfortunate not to start.
"It [where Weimann played] is a different position from the way Darren plays."