It might have been sick from when you got it from the store, that's not overly uncommon. A few of mine have passed even when they were placed into wonderful cycled tanks.
So I ask, do you know about the Nitrogen Cycle? I feel that in SW tanks it would be there, but I don't know enough about them to speculate.
Also most of those bulbs are probably duds, sorry to burst your bubble again >.< About 2 out of 10 will grow and that's with an extremely good luck and a good green thumb. I suggest taking them out before they rot unless you are confident that you can grow them
Plants that I do suggest you get or look into are Java Fern and Anubias, great low light plants, fairly inexpensive. One of my Anubias I've had for a year and it's flourishing so well! They're both low light plants and low maintenance so you basically rinse them off and plop them in and you're good to go! Just be sure to not bury the Rhizome. The rhizome is the part where roots come out the bottom and leaves come out the top, sometimes referred to as a crown. But the roots can be buried no problem. Both these plants will also grow on ornaments given time, just tie them on with fishing wire or regular thread and watch them attach over a month or so time.
Also what kind of Pleco's are they? I know you said albino but are they Commons? Or Bristlenose (BN)? Either way, BN's get up to 4-6 inches and Commons grow passed a foot. Soooo I highly suggest you return them to the store or find them a new home, even BN's need a 30 gallon minimum. All algae eaters are huge poop machines so the more poop you have in there the worse your Ammonia levels are going to be, that's why it's important to have the Nitrogen Cycle going. If you need help understanding it I can try to explain a little for you
There's also a great sticky on it in the Betta Habitat, Tank and Bowl section ^_^
I think I covered it all
great job with the 10 gallon and the dividers though!!