select payment method but nothing to select

I am using zencart 1.50 when you get to the check out page under Payment Method it use to show we accept Paypal now it shows nothing, I was using the standard paypal. then all of a sudden it was showing blank, paypal had disappeared. So I read the articles here and they say to use paypal express, so I uninstalled standard and installed express but I am still getting the same thing. Nothing appears under Payment Method. I get a red box at the top of the check out page telling me to choose a payment method but there isn't anything to select. Can someone help me please? I don't know if you need to know this or not but our product is download only, no shipping or tax. Thank you in advance for any help you can offer me.

When you installed Express, did you go through and set all the options to a correct getting for your site?

What do you have for:

1. Do you want to enable this payment module? Of course, it should be yes.
2. Express Checkout Shortcut Button. Turn it on if you want folks to skip the standard checkout.
3. Payment Zone. If you put something like Texas here, only folks from Texas could use PayPal. Normally, this is left blank.
   Also review other settings for accuracy.

Thank you for your response, I don't know what I did but it's working now. When you check out and the balance due is $0.00 then it doesn't show paypal at all, but if there is anything that is due at the time of checkout the pay with paypal button appears. Thank you again for your response