looks like you left the trailing / in the require once function.
Require once uses a relative path, so if the file the require once function is on and the connections folder are at the sam level, this should work:
if they are not at the same level, you may need to adjust the path:
Dreamweaver is using the "virtual" syntax because in your Site Definition, the "Create Links Relative To:" option is set to Site. If you change that to "Document" instead, Dreamweaver will use the "require_once"syntax.