Force CA validation

How can I force the CA validation on a EAP-TTLS configuration. If in my Windows-Supplicant software I select the CA validation, it works. But if remove it, and I use only the User-Credentials Authentication part... it works also. I would like to force that the CA certification Authentication part must be mandatory also. (I'm using windows-supplicant software with EAP-TTLS method) Thanks in advance, Swatzy.