What version of Premiere Elements and on what computer operating system is it running?
If you mention Expert, then you must be in either version 11, 12, or 13 Expert workspace?
For now assuming Premiere Elements 13 on Windows 7, 8, or 8.1 64 bit.....
1. Click and drag the right edge of the photo clip to the 17 seconds mark.
2. Right click the photo clip, select Time Stretch, and set the Time Stretch dialog's duration field to 17 seconds (00;00;17;00).
Any black borders you are seeing in the process could be the consequences
1. Not having set the correct project preset. Before you alter the photo duration, are you seeing black borders for the photo
when you are viewing the photo in the Edit area monitor?
2. The Video Display Format for the Video Track (has 4 choices to toggle through). To the left of the words Video 1 is a filmstrip
icon (Set Video Display Format). Clicking on that one click at a time brings up 4 different choices for video display format.)
Where is the type of display that is your issue - in the Timeline display or in the monitor display?
Please review and consider the above. If it does not target your issue, please give more details.