Error Running PS Script

Install-AdcsEnrollmentPolicyWebService -AuthenticationType Certificate -KeyBasedRenewal -SSLCertThumbprint (dir -dnsname cep1.corp.contoso.com).ThumbprintRunning the above command returns: Get-ChildItem : A parameter cannot be found that matches parameter name 'dnsname'.running Help Get-ChildItem, returns no parameter '-dnsname' Please advise.