Maybe take it a little slower...try a few more day naps in there so she is totally comfortable in her big girl room and then try then night sleep again.
If she is really getting quite upset and you push her she may build up a resentment and not want to go in there at all...just let her go at her own pace.
I did this and found after a few days to a week I had them in beds for night time too.
Perhaps that's a good idea... I kept reading that once I start not to go back, and we had success today for her nap so I didn't want to undo what we'd done... but I guess night time is a whole other story.

She's asleep now in her big bed, but I had to be in the room with her... poor darling wore herself out I think! Bad Mum award goes to me tonight, I hate seeing her upset because of something i've done. Not too sure what to do tomorrow now