Not sure if this is the right place to mention this, but it's the best I could find (i.e. no 'webmaster' contact link).
The page https://www.tixati.com/donate/
on your website states:
"PayPal Secure Payments Quick and easy, any credit card accepted, no PayPal account needed"
This may have been true at one time, but it looks like a PayPal account is now required, so you may want to update that.