function showError (id,classNameValue,buttonId,buttonClassNameActive,buttonClassNameInactive)
 {                                      
    errorContent=document.getElementsByTagName ('div');
    for (i=0;i<errorContent.length;i++)
    {
        if (errorContent[i].className == classNameValue ) 
            errorContent[i].style.display='none';
        if (errorContent[i].className == buttonClassNameActive )
            errorContent[i].className=buttonClassNameInactive;  
    }
    document.getElementById(id).style.display='block';  
    document.getElementById(buttonId).className=buttonClassNameActive;     
 }