Unable to load "wkhtmltox.dll" file in HTML to PDF Converter

Unable to load "wkhtmltox.dll" file in HTML to PDF Converter

  
Hello OS gurus
I am using "HTML to PDF Converter" and I uloaded (libgcc_s_sjlj-1.dll),(libstdc++-6.dll),(libwinpthread-1.dll) this 3 dll files.
but unable to upload "wkhtmltox.dll" this dll file.
Please help me out why this dll file is not uploading.

Thanks