Stopped by another Girls room.

I usually don't do this. But I stopped by another girls room. (Saw she was a successful gamer girl, with a similar weight and build as me. a vibe ive been going for) and that got me curious on how she does it. On stripchat. But I felt bad because I didn't want it to seem like I was stealing/bumming or anything so I went to leave a 20tk tip as like a "hey, don't mind me I'm going now" but it wouldn't let me tip! Can models not tip other models??