I very recently purchased a Den trantuanii that's in bloom with another bud and a tiny spike lower down. They're very charming plants and are reputed to be quite flexible regarding temperature range, relatively low maintenance, and easy to re-bloom, but some conclusive cultural information would help.
Marni Turkel shares some insightful care tips on her
website. She grows them in intermediate-to-cool conditions, which matches my indoor environment.
I thought this
article from the Vietnam Plant Data Center was also helpful. They tend to grow inland at higher elevations in a limestone-rich sub-tropical environment. I assume this means they prefer slightly more alkaline water and, come late autumn and winter, prefer to be watered less frequently and kept cooler. I suspect is key in getting them to spike. Hopefully those with more experience with this species can chime in!
(edit: Someone kindly informed me that Marni is not a male, so I edited my post accordingly. My apologies!)