no such file to load -- dbi (LoadError)

/home/mobo/mobo.tmp/mobo/dbi.rb:4:in `require'
/home/mobo/mobo.tmp/mobo/dbi.rb:4
(mobo.conf):4:in `require'
(mobo.conf):4:in `load'
/home/mobo/mobo.tmp/mobo.rb:356:in `load'
/home/mobo/mobo.tmp/mobo.rb:292:in `initialize'
/home/mobo/public_html/test/index.cgi:21:in `new'
/home/mobo/public_html/test/index.cgi:21