This has happened to me also. It was 15 years ago and it wasn't justified. I had been working at a HCA hospital and my son's 1st birthday was coming up. I got my shift covered and it was signed off as OK. Then I was told by my unit manager a week later that I had to work that shift. I had already planned a big party, spent too much planning it and a lot of people were coming. I told her I followed procedure to get my shift covered. She said I still had to work and I told her I couldn't and wouldn't be there but my cover was going to be working my shift. Next thing I know I'm terminated. I've had a hard time getting a hospital job since, and it was 15 YEARS AGO. What?!? I'd love to speak to you and/or anyone that's experienced being put on group one.