Make sure you haveenabeld the %Services_Binding in the services in security.  Must be on to use studio against database.

» %Service_Bindings Yes N/A Password,Unauthenticated Unrestricted Controls SQL or Objects

Did you check the owner and group of the /var/cache directory as well as its permissions.  It should be owned by the start/stop user defined during the install and with a group of cacheusr with permissions 775.  Also check the cache.cpf file as its permissions matter since this is an attempt to save the file before posting changes.