http://cvs.openacs.org/cvs/openacs-4/packages/acs-tcl/tcl/00-database-procs.tcl?r1=1.63.2.1&r2=1.63.2.2&only_with_tag=oacs-5-3 db_string was ignoring the -dbn switch.
You just need to update the file: /packages/acs-tcl/tcl/00-dabatabese-procs.tcl and reload the ac-tcl package from the APM.
Cheers.
I'll apply the patch. Thanks...