people having trouble with the $validfields thing, try this:
in the plugin manager, replace the entire code contents of the
vBCredits - Define User DM Fields
with the following
PHP Code:
$this->validfields['credits'] = array(TYPE_NUM, REQ_NO);
$this->validfields['credits_canearn'] = array(TYPE_BOOL, REQ_NO);
$this->validfields['credits_canspend'] = array(TYPE_BOOL, REQ_NO);
$this->validfields['credits_numrefs'] = array(TYPE_UINT, REQ_NO);
$this->validfields['credits_saved'] = array(TYPE_NUM, REQ_NO);
$this->validfields['credits_score'] = array(TYPE_INT, REQ_NO);
$this->validfields['credits_interest'] = array(TYPE_UNIXTIME, REQ_NO);
as for using this in a writing forum, you can make heavy use of the postsize award, so that users earn more for writing more, not necessarily often :-p but depends what you want to award them with
also, anyone interested in the changelog between 1.4rc1 and 1.4rc2, its been posted here
http://www.vbcredits.com/forum/showthread.php?t=1177