Is this the movie where.....

I don't know if anyone will know this or not because I don't think the movie was ever really popular. I think it's just a B rated movie but if anyone has any idea, please let me know. And it looked like an 80's movie but maybe it's a 90's or even 00's.

All I remember from this horror movie was that a group of 5 or 6 teens were going to put on this play or something in this old theatre and there was this teacher or instructor there too. They could have either been in High School or College but I'm not sure which. There was this stage and auditorium but it definitely wasn't an Opera house. It was this regular theatre that was in this city but I can't even remember the city. In the very beginning of the movie, the teens or young adults were all sitting in the seats of the auditorium and the instructor who looked 20 or 30 something was up on the stage telling everyone what their job was. Then the instructor left and the young adults were up on the stage cleaning up and then they talked about ordering a pizza. Then after that they were looking around this theatre and were trying to go into this dressing room but it was locked from the inside. Supposedly, there was a murder there years ago. This lead actress or singer but most likely she was an actress died in her dressing room. The young adults finally got into the dressing room and it was pretty big. The room was the size of 4X the size of the dressing room from The Phantom Of The Opera. So these young adults were checking out this big dressing room. Now, these young adults were supposedly the only people in the building at the time.

After they were done in the dressing room, this one couple, a guy and a girl started to mess around in it. This other girl went off to check out the costume room. She put on music and then this other girl went to check out the dressing room also. So these two girls were looking at the costumes, and someone else was just walking around and then the killer starts showing up and they start to die off. I also remember this guy going up into the attic. Basically the movie isn't a whole lot of action until near the end but I really like it and it's definitely not any version of The Phantom Of The Opera. If anyone has any idea of this movie, please, please let me know because I can't find any clues to getting this movie.