paypal donation button not working

[ctwoh]

My website was set up by our programmer adding the paypal button for donations... Now people have clicked on it to donate and a message comes up :

Your session is invalid or expired.

You've been inactive for a while, so we logged you out to help protect your account. Please return to the merchant and restart the payment process.

Does anyone know why this is happening and they can't donate?

[Quandary]

Would actually have to see the donation button code in order to assist.

[ctwoh]

Thank you all set

[BarrelsofFun]

What did you do? I thought I fixed the problem too, just to find out that the button expired, all over again.