validation control not working after OnClientClick added to button click event

actuallly i have to validate checkbox terms and conditions before submitting the form and to validate forms there is already server side validation controls are used. As there is validation controls not work on checkbox thats why i have written a javascript function to validate that checkbox but when i added the OnClientClick on that button , i checked that term and condition working perfectly but validation controls are not validating the forms. if i remove the onClientClick its works perfectly . finally with help of http://stackoverflow.com . i found the solution i have to explicitly call the validate function of server side validation controls and now my button html look like this :

OnClientClick="Page_ClientValidate(); IsChecked();" />