When I click on "proceed to checkout" button getting error

Question

When I click on "proceed to checkout" button getting error time to implement custom payment method.

config.xml

app\code\local\Excellence\Pay\Model\Pay.php

class Excellence_Pay_Model_Pay extends Mage_Payment_Model_Method_Abstract
{

    protected $_code = 'pay';
    protected $_formBlockType = 'pay/form_pay';
    protected $_infoBlockType = 'pay/info_pay';
    public function assignData($data)
    {
        if (!($data instanceof Varien_Object)) {
            $data = new Varien_Object($data);
        }
        $info = $this->getInfoInstance();
        $info->setCheckNo($data->getCheckNo())
        ->setCheckDate($data->getCheckDate());
        return $this;
    }

    public function validate()
    {
        parent::validate();

        $info = $this->getInfoInstance();

        $no = $info->getCheckNo();
        $date = $info->getCheckDate();
        if(empty($no) || empty($date)){
            $errorCode = 'invalid_data';
            $errorMsg = $this->_getHelper()->__('Check No and Date are required fields');
        }

        if($errorMsg){
            Mage::throwException($errorMsg);
        }
        return $this;
    }
}

The Error is:-

Answer 1

Alright, the issue is in the config.xml like I suspected.

More specifically you call for a model called pay/pay which doesn't exist for it is searching in Mage/{first_key}/Model/{secondary_key}.

I took a quick look but I couldn't find which model you have to extend, but the issue is at default -> payment -> pay -> model