Hi David,
Yes, it's fine to leave the subjectname parameter empty since the search query process before populates this field for you.
Are you sure your search query is appropriate? Raw files are typically all named "Link to raw file" yet you're trying to find one with the keyword "resample", so there are probably simply no matches. You can test your query from the GUI by clicking the magnifying glass icon at the top right of the Brainstorm database and pasting/typing your query. If you are looking for a raw file whose parent folder contains the word "resample", the following query would be more appropriate:
(([type EQUALS "RawData"] AND [parent CONTAINS "resample"]))
Best,
Martin