We can guarantee that every hint is playable with the letters you have. It only looks at your letters and the letters on board to find words. This thought sometimes occurs when there is a blank (wildcard) in hand which can be used as any letter. If you have the hint word and think this happens you can send us a screen shot and the hint word after the play and we can sort it out. Thanks!
To do a screen shot tap the home button on the front of device and the lock button at the top at the same time. This will put a screen shot in your pictures. Go to your pictures app and you can email that picture to firstname.lastname@example.org.