Error message about table prefix

Hi there,

I'm trying to run a merge from "Burning Board® Lite Version 2.0.1 pl 1 (Nova)" to MyBB 1.8 using "MyBB Merge System - Version: 1.8.11".

I'm getting the following error message:

There seems to be one or more errors with the database configuration information that you supplied:

The WBB 3 / Lite 2 database could not be found in 'dbctf9vx'. Please ensure WBB 3 / Lite 2 exists at this database and with this table prefix.
Once the above are corrected, continue with the conversion.

I logged into the phpmyadmin, and the database name and the table prefixes are set correctly starting with wcf1_ or wbb1_1_  (e.g. "wbb1_1_board")
In wbb3.php it also looks correct:
define("WCF_PREFIX", "wcf{$this->installationnumber}_");
define("WBB_PREFIX", "wbb{$this->installationnumber}_1_");

Any suggestions how to solve this? Or can I set the "Database Configuration" manually in a file and mark the step as completed?

Many thanks,
Robert