google drive api partial search results

google drive api partial search results

I am using Google Drive API from Google App engine for java. I am
searching the google docs with search string
Files.List request = service.files().list().setQ("title contains
'Donation'");
It returns only 2 files with title DonationThankYouLetterData and How to
Create Awareness on Blood Donation
I failed to understand why it is not returning other files with title like
DonationThankYou_Anil Kumar _02-Aug-2013 Donation
All files are created by me so owner is same.