Custom Validator Question

I have an ASPX page with a ASCX control on it.  In the ASCX control I have validation going on and I just added a CustomValidator.  On the ASPX page there is a save button that I have causesvalidation = true which works fine with the required fields etc.   I dont want the user to move on unless they have saved a part of the ASCX control area.  My code fires off on the ASPX button continue but it does not stop on that page and show the custom validator even when I am setting IsValid = false.  Any ideas?  Here is what I have:

ASCX Control:
<asp:CustomValidator id="CustomValidator1" runat="server" display="Dynamic"  text="*" ErrorMessage="You must complete the Personal Information to continue" OnServerValidate="Validate_Save"/>  

Code Behind:
protected void Validate_Save(object sender, ServerValidateEventArgs e)
    {
        if (Session["PersonalSaved"] != null)
        {
            if (Session["PersonalSaved"].ToString() == "saved")
            {
                e.IsValid = true;
                return;
            }
            else
            {
                e.IsValid = false;
                return;
            }
        }
        else
        {
            e.IsValid = false;
            return;
        }
    }

Gets into that last e.IsValid = false then drops out and my next page loads from the Continue button on the ASPX page which I dont want.  I need it to stay on this page and show the error.  Thanks all