A response of 'Invalid Password' could be caused by several reasons.

Terminal Response	Probable Cause	Solution
Invalid Password	The password was input incorrectly.	Ensure that the password was keyed into the terminal correctly.
	The standard password on the terminal has been changed.	Try:  000000, 0000, 1, 998877, 1234, 123456, 23378463, 1701, or no password at all.  If none of these passwords are successful, refer the merchant to the credit card processor to obtain the correct password.