you should be able to do this no problem.
My station is configured this way. When a dj connects it fade autodj out and the live dj in, when live dj is disconnected he is faded out and autodj fades back in.
It may be a setting not right in butt or your dj accounts aren't set up properly.
When using butt even if your server is on V2 you have to use V1 settings in butt for dj:password and server.