Tilt is back in South Yorkshire after his loan spell at Wigan was cut short when the two clubs could not agree a fee.
Warne thought a deal was going to be agreed earlier in the week but it has not happened and although a move before the end of January still seems likely, the 30-year-old could yet end up staying with the Millers.
“Earlier in the week, I was pretty confident that something definitive would have happened by now, whether that be Wigan or another club purchasing him,” he said.
“I thought it would have been done by now but it hasn't.
“I now regard him as my player until I'm told differently and I'll get him ready with the rest of the squad for Saturday. It hasn't materialised the way I anticipated.”
The 30-year-old, who cost the Millers £100,000 two years ago, is desperate to move to the DW Stadium and is regularly talking to Warne asking for an update on the state of play.
Warne knows he will have manage Tilt carefully if a move does not go through.
“It's why you're called a football manager - you have to manage people,” the boss added.
“That part of the job is probably greater than the tactics and getting players to run through brick walls for you.
“I will talk to Curtis. I do talk to Curtis. I've been on the phone to him twice a day at least for the last five days. I explain it to him as honestly as I can.
“I don't make every decision at the club, quite obviously. I guess the manager of Tottenham sat down with Harry Kane when Kane's move to Manchester City didn't happen. That's how football is sometimes.
“If Curtis stays, he knows I rate him as a player. We'll do everything we can to help him compete with the lads who are doing well.
“I haven't got a magic wand that I can wave and he's like, 'Yeah, I feel amazing, Gaffer.'
“I know he's not going to be fully on board but he's a professional and I expect him, as a professional athlete, to knuckle down and join in with the group.
“He'll soon be incorporated and welcomed back into the group. In a couple of weeks' time, it might be a distant memory for him.”