When you use fileattrib, catch the success and the error message also:
[status,msg,msgID] = fileattrib('D:\work\results','+w')
What do you get? You cannot change the permissions of a folder, if you do not have write permissions to it. Actually you should not even be able to create a folder without write permissions. So how did you create it at first?
Will the problem occur repeatedly? If not, use the Security tab in the "Properties" of the folder, which appears in its context menu in the Windows Explorer. Perhaps the permissions of D:\Work are restricted already. Then fix this folder also.