Updating pages causes "White Screen"

Hi Heba,

i’ve checked my site. I installed Yoast SEO. Since this i can not update pages any longer. When i want to update a page it causes a white screen. Deactivating Yoast SEO and then it works. Debugging wordpress when i click on “update” will give me this information:

Fatal error: Call to undefined function putRevSlider() in /usr/www/users/projekyr/tvw/wp-content/themes/sarraty/framework/aqua/blocks/aq-revslider-block.php on line 67

i’ve uploaded a old version of aq-revslider-block.php but this is not working.