Better than a 6-pack, I have a pony keg.
Seriously, though. The lower abs are THE HARDEST to get to show IMO. It may be that your BF is still too high.
However, If your lower abs are lacking, it may be the order you're training in. Make sure that you train the lower abs first, then the next weekest part of them, ending with (or even skipping from time to time) the strongest part to regain (or gain in some cases)
symmetry & balance.
Additionally, you use the lower abs, to an extent in all of your ab routines, so if you work anything else first, you can't isolate the burn to the lower portion once it's their turn.
The other thing to look at, is are you over training them? - and this part is controversial, so flame on if you must - there is a philosphy floating about, that the abdominals should be trained like any other muscle group. In most cases, that is once or twice a weak, just like your bis, tris, pecs, lats, etc. Many guys train abs every workout day, either as a warmup to other routine, or as an integral part of every workout. Most people would NEVER train any other muscle group in that way. In a nutshell, if you're already training them daily (or every workout) back off. Instead, once or twice a week (like the other parts), super blitz them. Starting with the lower abs, then say upper, then obliques, then intercostals. Hit em from every angle and hit them hard, but only hit them with the weekly frequency that you do your other body parts.