ASP.Net MVC Web Config Error: Unrecognized element add

I deployed my Asp.net Mvc to Go daddy(plesk) I got Error to open my index page.

i googled it and i added to some code to web.config.

"<add assembly="System.Runtime, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" /> "

but i got this error "Unrecognized element 'add'."

Source Error: 

Line 19:     <trust level="Full" />
Line 20:     <compilation debug="true" targetFramework="4.7.2" >
Line 21: 	<add assembly="System.Runtime, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" />   
Line 22:     </compilation>
Line 23:     <httpRuntime targetFramework="4.7.2" />

I have no idea..

please help me someone for this issue..