Actually, the Repository _may_ be the problem. Does the repository point to a valid 5.8 location, or does it point to a 5.6 repository? Does the repository have a DBI package for 5.8? Type rep then rep desc at a ppm prompt. Mine looks like this:
in reply to Re: ppm trouble:'no suitable installation target'
in thread ppm trouble:'no suitable installation target'
ppm> rep desc 2
Describing Active Repository 2:
Name: ActiveState Package Repository
Type: PPMServer 3.0
If it does point to a 5.6 repository, see DigitalKitty's post above to point it to a valid 5.8 repository.
BTW, the target looks fine, except for the extra 'v' in ActivePerl (which won't make any difference).