cannot find certificate local machine root store even after granting access apppool user

hi all, I have installed a certificate that has to pass into a httpwebrequest to access a third party API.. so I have installed certificate into local machine root store and granted access to IIS application pool identity user using winhttpcertcfg 

C:\Program Files (x86)\Windows Resource Kits\Tools>winhttpcertcfg.exe -g -c local_machine\my -s "certificateissuedname" -a "servername/apppoolusername"

I have tried below code to find certificate but no luck certificate count 0.

X509Store keystore = new X509Store(StoreName.Root, StoreLocation.LocalMachine);
keystore.Open(OpenFlags.ReadOnly);
X509CertificateCollection certs = keystore.Certificates.Find(X509FindType.FindByThumbprint, "‎‎‎19 27 d4 55 b3 j7 55 d1 78 a2 63 99 5g 25 gg 65 t5 t5 05 8c", false);

if (certs.Count > 0)
{
return  " found cert on local root ";
}

I have change StoreName to my no luck

anyone to help