New-SPWebApplication : A valid object could not be read from the provided pipe bind parameter.

So, you're trying to create a Sharepoint site with powershell, and you're getting this error.

It's because you forgot to specify the authentication provider.

$ap is just a variable, and it's probably empty.

You need to do this first:

$ap = New-SPAuthenticationProvider

 or

$ap = New-SPAuthenticationProvider -UseWindowsIntegratedAuthentication