Peoblem to display the charts in IE7 andIE8

i am working in mvc3 project. i am use the dhtmlx chars in my project. these charts are shown in the fire fox, Google chrome and IE9 but these charts are not shown in IE7 and IE8.
if somebody having any solution related to my problem. please reply on my email

Make sure that thirdparty folrder is in the same directory as dhtmlxchart.js. It is necessary for charts in IE.