Pro-Site Payp button only refresh and coupon not apply

Hi there,

I hope all is well with you today. I have a fresh WPMU installation and Prosite is the only network activated plugin and using WP 2015 themes. here's my problem with ProSites

1. am unable to apply a coupon . when click on apply coupon it doesn't do anything
2. when i choose a plan and try to checkout with the paypal button, it just refresh the page.
3. the Coupon field only shows when i enable 3 or 12 month price in Levels section.

Ps. Support access already granted, if you're unable to access the website , please send me your IP address so i can whitelist it.
Thanks in advanced.