SharePoint 2013 Office web app server configuration Unable to create New-spwopibinding in SharePoint. getting below error.

I have created new office web app farm for SharePoint. but unable to create SP-WOPIBINDING in SharePoint farm. Please check below error. when I have configured office web app farm that time I have used Wild card certificate for farm creation.

WARNING: The server did not respond. Trying again (attempt 1 of 5).
WARNING: The server did not respond. Trying again (attempt 2 of 5).
WARNING: The server did not respond. Trying again (attempt 3 of 5).
WARNING: The server did not respond. Trying again (attempt 4 of 5).
WARNING: The server did not respond. Trying again (attempt 5 of 5).
New-SPWOPIBinding : Sorry, we have encountered an error and New-SPWOPIBinding
has failed. If you are using a server configured with HTTP, you must include
the -AllowHTTP parameter.

Also I have checked the Event viewer in SharePoint then I found below error.

An operation failed because the following certificate has validation errors:

Subject Name: CN=*., OU=, O=, L=, S=, C=IN
Issuer Name: CN=, OU=www.digicert.com, O=DigiCert Inc, C=US
Thumbprint:

Errors:

 SSL policy errors have been encountered.  Error code '0x2'..

Please help me here. Please.