Cannot connect to database - Joomla! Forum - community, help and support

i'm bit embarrassed post problem. have debveloped number of joomla sites without hitch.
i transfering site own dev domain clients domain.

normally edit configuration.php
temp url
logs url
database url = localhost
db name
db user
db password

i have done these, double checked them , triple checked them still "cannot connect database"????
is there else should checking?

evidently on of values listed incorrect. database host "localhost"? if mysql on different server host have different title.