Console error after pressing the Paypal button

Hi I have installed your plugin on the nopcommerce 4.0 platform. I have also set up all the credentials.
The problem I have is when I click on the paypal button and it comes back with :

Failed to load resource: the server responded with a status of 404 ()  logger.js:63

Uncaught Error: Request to post /paypalexpresscheckout/createpayment?IsCheckout=False&useRewardPoints=false failed with 404 error. Correlation id: unknown
    at XMLHttpRequest.<anonymous> (http.js:114)
    at Object._RECEIVE_MESSAGE_TYPE.<computed> [as postrobot_message_response] (types.js:121)
    at receiveMessage (index.js:114)
    at messageListener (index.js:140)

Any suggestions ?

Thank you

Do you use live or sandbox credentials?
Clear the browser's cache and try again.

I am using sandbox credentials. I've cleared my browser cache as well as the website cache and it did not have any effect. Any ideas what it might be ?

I don't know. I'll try to help you. I checked it on test store and it worked.

1. Make print screen and send me (support@foxnetsoft.com) the page with this error message.
2. Did you try to checkout from shopping cart page or from payment info (from checkout) page?