This is a problem that happens when you set the option in your site definition to Use Site Relative inks instead of Document relative.
In the Site definition settings, one of the options is:
"Links relative to"
When you select the Site Root setting, dreamweaver uses the virtual() function for linking helper files like the Connection, for example:
<?php virtual("/Connections/databaseConnectionName.php"); ?>
the virtual() function is only defined in some installations of apache, it is not defined most of the time.
When you select the Document option, that will cause Dreamweaver to use the require_once function for linking helper files:
<?php require_once("Connections/databaseConnectionName.php"); ?>
you should use document relative links in the site definition settings to prevent this error.