Validating on tab

Hi I have been struggling with this for a few weeks now all suggestions do not seem to work. I am writing a program which validates well on the return key but as many users especially experienced one like to use tab and therefore go though my program with no validation, i want to validate on tab too or disable it. I have tried the keyascii for tab which is 9 but this does not seem to work. I have tried validation on a lost focus but just got into a messagebox hell with everytime you left a box with nothing in it threw up a messagebox good butwhen you tried to set the focus back to the original text box you got another lostfocus empty box messagebox from the one it had just left. I have tried vbtab but thast did noty seem to work and tried chr(9) with no success. Please oh people with brains and exquisit knowledge help me out here

nuts