Did you use OEM honda fluid? The correct fluid is very important on these cars.
What did the old fluid look like? Was it really black and nasty? The problem with changing fluid on a tranny that's been neglected is there can be sludge build up, which the new fresh fluid starts to dissolve. Chunks of solid crud can come loose, circulate, and clog things up.
If the old fluid was in poor condition, it might be worth taking it to a shop for a chemical flush. Unfortunately there's no guarantee that will work, but probably worth a try. Otherwise might need a rebuild.
It could be a solenoid valve that's clogged but it could also be internal passages.