Caps-Lock Detector shows on even caps lock is not on

function AlertIfCapsLockOn(eventArgs) {

            var keyCode = eventArgs.keyCode ? eventArgs.keyCode : eventArgs.which;
            var shiftKey = eventArgs.shiftKey ? eventArgs.shiftKey : ((keyCode == 16) ? true : false)
            var isEnabled = CapsLockEnabled(keyCode, shiftKey);
            if (isEnabled) {

                toolTip.show();
            }
         }

        function CapsLockEnabled(keyCode, shiftKey) {

            if (((keyCode >= 65 && keyCode <= 90) && !shiftKey) || ((keyCode >= 97 && keyCode <= 122) && shiftKey))
                return true;
            else
                return false;

        }

<asp:TextBox ID="Password" runat="server" TextMode="Password" Width="150px" onclick="return AlertIfCapsLockOn(event);return false;"
                                                Height="5px"></asp:TextBox>
                                            <asp:RequiredFieldValidator ID="PasswordRequired" runat="server" ControlToValidate="Password"
                                                ErrorMessage="Password is required." ToolTip="Password is required." ValidationGroup="log">*</asp:RequiredFieldValidator>
                                            <telerik:RadToolTip ID="radtooltip" runat="server" Text="Caps Lock is On" ShowEvent="OnFocus"
                                                TargetControlID="Password" Position="BottomCenter" RelativeTo="Element">
                                            </telerik:RadToolTip>