dendrobium help

[StevenU]

Hey dendrobium lovers, I would appreciate your advice. I grow many different orchids and have no problems getting them to bloom and flourish, not so with dendrobiums.

Bought one (typical garden store variety) in hawaii 3 years ago. It has bloomed but on the old growth, but I cannot get it to put out any new canes. I did get one keiki but even that didn't grow when I potted it up for two years. Its roots never grew past the point where they were when I removed it from the mother plant.

I put the plant outside for the summer and in a south window in the winter (Minnesota winter sun is pretty weak). I fertilize as well.

Just bought a D. nobile and don't want a repeat performance on this one.
Ideas?