Force CA validation

[Fernando Calvelo Vazquez]

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.