You need to adjust the path to your current excel.exe. Noticeable is that these excel will be run like a background-service - it meant it won't be visible - maybe it could be changed by the excel-macro which needs to run with an OnOpen-trigger in this case. Therefore it could be helpful to include such things like a run-parameter.
Another possibility would be to use a dertour and start a windows tasks which then started your excel which I for example use if I need that the tasks runs with a different user:
How had you tried it - reloading the qvw within the desktop client or manually triggering the task within the qmc or per scheduled qmc-task. If not yet done - try it in the above mentioned order.
One reason could be that you hadn't enabled the execution of the EXECUTION statement. There is a setting within the user-properties within the tab security and also within the settings.ini from the server (it's different by older and youger releases): Authorizing the Script EXECUTE Statement | Qlikview Cookbook.
If you are running this from the desktop client and it did't work it meant that there are certain settings on the windows-task which prevent the external execution from the task - or meant it didn't work the task will be executed but the export failed?