if you have too much water near the "root" part of the brom, it will die.
they grow on tree branches and such in the wild, so planting it in soil is
risky. you need high draining soil. plus the company that you bought it
from should be able to solve your problem, if not, don't shop there again.
some broms have a root structure that is developing, that needs a bit of peat or other substrate but it can't be wet. just damp. others just have a sort of stick, which looks like it could be planted but it would be best to drill a hole in a branch, and then set it in place. wire some spag-peat around the base with fishing line for a while; until the roots start to take hold.
that and maybe stronger light, not sure what you have or how far the brom is from the lights. CF's at 10,000k are all i use now, but was using 5.0 and 8.0 flors for most tanks.
hope this helps.