You will want to add the gallerycode to 3 locations.

1. It should be added to the survey. Make sure not use the percent signs in this area.

2. You will want to add it to the output template. It should be surrounded by percent signs to capture the variable text. You can also hide the text behind other objects so that it does not show.

3. The third place to add the gallerycode is to the Post to Event Gallery options under Event Name. Also, be sure to check the option for the date.

Click on the screenshot below to zoom in and enlarge.