PayPal - Woocommerce - doesn't work. What is problem?

[Enikam]

Hello,

I installed plugin PayPal PLUS for Woocommerce and went through setup.

When I insert Client ID and Secret ID it's written that everything is ok and settings were saved.

But when I want to buy a product and I chose PayPal as payment method I see message: 

"Sorry, at the moment no payments can be processed for technical reasons."

Please help me. Where is the problem?