Error 'namespace name 'NVPAPICaller' could not be found' while integrating payment Geteway in ASP.Net

Last Reply on Jul 18, 2016 07:20 AM By Shashikant

Posted on Jul 18, 2016 06:19 AM

I have tried this thing :

but i am getting error 

namespace name 'NVPAPICaller' could not be found (are you missing a using directive or an assembly reference?

in expresscheckoutpage.aspx.cs file