HTML

<asp:Button ID="btnFromCalOpen" runat="server" Text=" &gt; "  onclick="ShowCal()"  CssClass = "SElementHide" />

使用Javascript

function ShowCal() {

    var elem = document.getElementById('MainContent_CalendarFrom');
    if (elem.visibility = "hidden" )
    {
    elema.style.visibility = "visible";
    elema.style.display = "block";
    }
    else
    {
    elema.style.visibility = "hidden";
    elema.style.display = "none";
    }
}

错误
编译器错误消息：BC30456：’ShowCal’不是’ASP.default_aspx’的成员.

请帮忙