Win2012R2 DHCP exclusion partially working: confused

Hi. First post here.

We've DHCP setup in a Win2012R2 server.

DHCP range: 192.168.100.50 to 192.168.101.254

Exclusions:

192.168.100.61 to 192.168.100.70 - works fine. these IP addresses are not handed out

192.168.101.61 to 192.168.101.70 - does not work fine. DHCP hands these out like candy

Is there something here that I've overlooking?