Check if you configured your device to be recognised as USB-Mass Storage, if yes then this is your problem. there are many pips who reported this issue. phone doesn't charge if connected as mass storage. change to Active Sync.
this should solve your problem, and be sure turned backlight off, will charge much faster
i facing the same problem now, phone can charge only when switch off.
(i had check the and sure the device is in activesync mode, now i only can sync my phone though bluetooth, and octon also cannot recognised my phone)
i had search the other forum, some omnia II user have the same problem, they solve by hard resting the phone.
i had try hard resting the phone but still not work.
I have same problem with my Power Monkey charger. It has std. 5V USB, connector USB A/female and up to 2,1A output and still can't charge my B7610 :-(, it can do it only when the phone is off. Same problem in my car, where is reduction 12V -> 5V USB. Somebody talked, try to connect Data- to Data+ on USB...