I have D-Link DUB-H7 with 7 ports. It works fine except I cannot use my external HDD with it. HDD clicks, but it seems not enough power. Connecting of 2nd HDD's wire doesn't help.
Based on the fact that your HDD is intended to work with simply a single USB 2.0 port, I'm going to assume that it's simply a bit of a power consumption issue and a simple powered USB hub will fix your issues. There's a wide variety of USB hubs available, but this one is by a reputable manufacturer, comes in a nice form factor, works with or without power, uses USB to deliver additional power, supports USB 3.0, and is fairly cheap.