Hello,
Please open your browser console (also called "developer tools") to see the Javascript errors.
If you just have that message, it means that the Stripe JS Library is not initializing ; it will give you the reason of that issue.
I might be incorrect credentials if your account is not authorized for production mode.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.