In the Server Validation code there is a line like this:
PostResult($WAFV_Redirect,$WAFV_Errors,"usersRegistration");
Then each validation reference looks like this:
ValidatedField("usersRegistration","usersRegistration")
or
ValidatedField("usersRegistration","fieldName")
You need to make sure those values match... the argument to PostResults() must match the argument to ValidatedField().