Cannot charge venue 8 from TrippLite TLP606USB

I have a few TrippLite TLP606USB and cannot charge my Dell Venue 8 from the USB port on them.  I am able to charge other devices and charge the venue 8 from other USB ports such as the one that came with my phone or from my laptop.  I see Dell sells the TLP606USB in the accessory store, can someone at Dell check and see if/why it will not charge?  I am using a StarTech USB to right angle MicroUSB cable which will charge other devices fine from the TripLite and will charge the tablet fine from other sources like my laptop.