Try to specify only the folder for the filename parameter. To quote MSDN:
filename : Name of the export file. If using the –nofilecompression parameter, a directory must be specified; otherwise, any file format is valid.
In your sample you seem to use the nofilecompression switch - in that case the export process would produce a set of files and store them in the specified folder. You can either:
- remove the parameter so that the export outputs only one file or
- modify the filename to include only the folder
Note also that the first option would usualy require more time (compression will slow down the export process - but it sure is easier to store only a file).