Is there any way to view dpm() data other than printing it on page?
I know you say you are logged in as admin but even so just check the permission "Access developer information" is checked for the admin role just in case that makes a difference.

I've also heard of dpm not working as a result of modules not being uninstalled before they are deleted. Maybe try this module to see if that helps.

Another option would be to see if kpr() works instead.