My guess is the quality of the maribou you used..If you've tied many bucktails,you know some of the tails are great to tye with,and others are just good for the trash can.Maribou is the same way. I'd try purchasing maribou from a fly shop or online supplier.
If your looking for a strong substitute for maribou with similiar action,try Icelandic sheep wool.It's about 8" long.Cut off the amount you want,run a comb through it to remove the under fur,and reverse tye it.What I mean by reverse tying is point and tye in the fibers facing out over the hook eye instead of the bend of the hook.When you have the fibers tied in,pull them back towards the hook bend,and cut them too the length you want.It now looks like a out of control umbrella..don't sweat it,when the fur gets wet,and the lure is worked through the water,the fibers will pull back over the hook bend,but when you slow the retrieve down or stop it,the tail really flares out..Nathan