I'm sending json data with errrors back to script, but it won't stop at the messagebox (displaying errors), just moving on. This should be a easy error made by a rookie 
Code:
...
register_user.addButton('Register', function(){
if (register_user.isValid()) {
register_user.submit({url:'insert_user.php',
waitMsg:'Please wait...',
success:function(form, action){
Ext.MessageBox.alert('', action.result.msg);
location.href = 'reg_complete.php';
}
});
}else{
Ext.MessageBox.alert('Errors', 'Please fix the errors noted.');
}
}, register_user);
register_user.render('form-ct');
})