@joop To best diagnose the problem that you are experiencing, it would be helpful to have a copy of your project. Could you share it via dropbox or google drive? You can send it to me at chris underscore hubbard at sil dot org. Thanks.
If you are modifying the source USFM files to add illustrations, then it would be better to use the illustration placement functionality. Double-click on the illustration and then click the “Add Placement…” button to specify where the illustration should be placed.
There were 2 issues that kept it from working:
You misspelled the src attribute and used scr instead
There was a space between the | and the first attribute
While looking at this issue, we noticed that using the illustration placement was not including the optional caption. It has been fixed and will be included in SAB 8.4.