Speaking to the media, Howe said: "My wish was for us to do our business early, and we certainly tried, but it wasn't to be. We've had a frustrating time in terms of losing targets to other clubs. I'd be very open with that.
"That's happened on several occasions. You just have to accept it. In order for a transfer to really work, in my opinion, the player has to be desperate to come to your club. If we don't get that, the transfer doesn't work.
"We're seeking players that are good enough, that are desperate to come, and that can make the difference, that they're in short supply for us.
"We're confident that we can try and get some more players in to strengthen the depth of the squad. We're certainly aware that we need to, and we're trying as hard as we can to do that."