asp.net validation related problem

This event belongs to form view

protected void companyForm_ItemInserting(object sender, FormViewInsertEventArgs e)
{ 
    some logic 
}

I have some customValidator (server side) i want to know y i dont need to check page.isvalid property in above event... while in so开发者_StackOverflow社区me events i have to check it otherwise event code is processed despite failure of validation...