Javascript Creating Excel

I got the following error even the document itself and its parent/children folders are writeable. The IURS_machinename has all the Administrator permissions (NOT Guest group). The "test1.xls" document is editable through Excel.

Error Type:
Microsoft Excel (0x800A03EC)
Cannot access read-only document 'test1.xls'.
/CreateExcel.asp, line 222

The following is the code .......

var ExApp = new ActiveXObject("Excel.Application"); // This is line 222
if (ExApp != null) {
ExApp.Visible = false;
ExApp.Application.Workbooks.Open("c: est est1.xls");