Dynamic economy and permissionsex don't really work toghter nicely.
I can assign Dynamic economy permissions to people but they cannot auctally use the plugin, it just says they dont have the permission to use it.
According to the developer of the plugin its a vault issue and i would kindly ask you if would take the time to look into it.

~ Eternia

Then its a proble of Dynamic economy, vault works fine.

Vault's permission checks work great, I'd suggest checking PEX to make sure you aren't using something like case-sensetive permissions, or another setting that will mess up how Vault is checking the permissions.

Well honestly the one developer refers you to another and the other sends you again to another one.
Its has been tested with case-senstive issues and both failed.
Most people who use the combination Dynamic economy, vault and permissionsEX just dont seem to get the permissions working.

My avatar applies to MFW people keep redirecting you.

I'll re-iterate what I've told people in the past. generic permission checks are passed off to bukkit even though it looks like Vault is handling them it's not. Vault simply says oh PEX supports superperms -> do player.hasPermission("blah").

So the issue is most definetely with PEX, or DynamicEconomy. generally the blame lies on how the Permission System is handling the permission checks and how DynamicEconomy is checking permission. If I remember correctly PEX overrides the player object and handles them itself (in a case-sensetive way) when normally Bukkit doesn't do case-sensetive checks. So this will cause problems.

Alright ;)
Thanks for the clear answer, ill take this issue on to PEX then.