If, as in your previous question, you are using this value to create a file, it may be that it's the space before "to" that is causing the problem. Try to use:
"Report("
+ System.DateTime.Now.ToString("dd-MMM-yyyy")
+ "To"
+ System.DateTime.Now.AddMonths(-1).ToString("dd-MMM-yyyy")
+ ")"
instead and see if that fixes it.
If that does fix it, you'll probably need to either figure out how to quote the entire file name so it's not treated as the three separate arguments, "Report(29-Dec-2009"
, "to"
and "29-Nov-2009)"
. Or simply leave your reports names without spaces.
I'd choose the latter but then I'm fundamentally opposed to spaces in filenames - they make simple scripts so much harder to write :-)