Note that ping may use other means to resolve hostnames than DNS, and that Windows OSs often assume they have to append the local search suffix to plain hostnames (i.e. an application issues a request for laptop, but Windows then requests e.g. laptop.lan instead or in additon to the plain request).
Since you only added Local DNS records for plain hostnames, it is likely that some lookups fail because you are missing the respective FQDNs. Please see [SOLVED] How can I get the local domain name auto suffixed to hostnames in DHCP? - #2 by Bucking_Horn for a few additional options.