Rafael Benitez admitted he was surprised by Newcastle's lack of activity in the transfer window.
Benitez's side missed the chance to go top of the Sky Bet Championship when Ciaran Clark's late own goal consigned them to a 2-2 draw against QPR.
Newcastle did not add to their squad during January, leaving their manager to cope with what he has already got as he tries to lead the club back to the Premier League at the first attempt.
A tetchy Benitez said: "I can't change things now. We knew what we needed and we knew what we have.
"I'm disappointed (not to have signed anyone) but I have to concentrate on the players we have."
When asked if he was surprised at the club's lack of signings, he added: "Yes." When questioned if he could reveal what went wrong on deadline day, the former Real Madrid boss said: "No, because I don't know."
Benitez knows his side need to be more clinical if they are to be promoted.
Yoan Gouffran and Ayoze Perez both wasted glorious opportunities to seal the three points before Clark's goal.
"We had a lot of chances but we didn't take our chances and we conceded with an own goal which is the worst thing that can happen," Benitez said.
"We didn't take the chances that we had. We needed to score the third goal but we didn't do it.
"We're all disappointed that we couldn't get three points."
Jonjo Shelvey had given Newcastle the lead after just 38 seconds but Conor Washington's equaliser before the break was a deserved one.
Newcastle improved after the break, with Matt Ritchie heading in his fifth goal in four games, but it was not enough to earn three points.