Phantom power question

[wintoid]

I'm using an RME Babyface Pro sound card, which is a USB device, and powered entirely from the USB connection to my computer (Mac Mini).  I've treated myself to a preamp/active DI box, which is the EBS Microbass II, and supposedly this can be powered over XLR phantom power.

So, I've connected the Microbass to the Babyface using an XLR cable, and powered it from a 9V battery initially.  No problem, this works OK.  I've been into the RME TotalMix software, found the bit where phantom power is turned on, and done that, which results in an orange light turning on on the Babyface.  However, the Microbass is not detecting the phantom power.

Am I missing something obvious?  Is there not going to be enough juice for a USB-driven soundcard to also power an active DI box over phantom power?  Did I need to ensure my XLR cable had some particular characteristic to get this to work?

Any help much appreciated.  I literally have never used phantom power before, so I know nothing about it.

[jrixn1]

Maybe check that the Microbass's ground lift is not engaged, because removing the ground also disables phantom power as they are the same circuit (I think in general, not just on the Microbass)

[wintoid]

Oooh!  Thank you!  Just briefly tried this and it looks to be the solution.  I was sure I'd tried that, but obviously not.  Thanks so much for your help.