function SinhNgay()
	{
		var svalueThang;
		var svalueNam;

		ArrSongay= new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

		svalueThang = frmDangKi.sltThang.options[frmDangKi.sltThang.selectedIndex].value;
		svalueNam = frmDangKi.sltNam.options[frmDangKi.sltNam.selectedIndex].value;
		if(svalueNam == "0" || svalueNam =="")
		{
			frmDangKi.sltNgay.options.length = 0;
			frmDangKi.sltNgay.options[0] = new Option ("Day" , "")
			frmDangKi.sltNam.focus();
			return;
		}
		if (svalueThang =="0" || svalueThang =="")
		{
			frmDangKi.sltNgay.options.length = 0;
			frmDangKi.sltNgay.options[0] = new Option ("Day" , "")		
		}
		else
		{
			frmDangKi.sltNgay.options.length = 0;		
			frmDangKi.sltNgay.options[0] = new Option ("Day" , "")			
			nNam  = parseInt(svalueNam);
			nThang = parseInt(svalueThang);
			nNgay = ArrSongay[nThang-1];
			if(nThang == 2)
			{
				if( nNam % 4 == 0 && nNam % 100 != 0)
				{
					nNgay=29;
				}
			}
			
			for( i = 1; i<= nNgay ; i++)
			{
				frmDangKi.sltNgay.options[i] = new Option (i , i) //new Option("text", "value")
			}
					
		}
	}