Join form not working

Hello,

I have amended the join form and added some new fields but now when I complete the form and enter submit I get a blank screen just saying 'error, database query error'.  How can I find out what the problem is here?  Is it that I've added some new fields or is it because I've not configured what should happen next after submitting a join form?  

Any advice would be great.  

Ta very much.  

first of all go to /inc/db.inc.php file find line

define( 'DB_FULL_DEBUG_MODE', false );

and change it to

define( 'DB_FULL_DEBUG_MODE', true );

It will turn on debug mode - and you will see a reason. After it you can PM me with details

Regards

Artur