Hi ydgmms,
dpderr used the Isobuilder that is in the Garyopa package, it is the simplest solution you can find.
If you want to include DMI, PFI and a Video.iso you should use ssmerger. I used SSmerger but did not include a video.iso (instead I used Pad with blank option), also I did not take the NME Iso option (needed only if you have an NME chip).
Two options: one simplest , the other a bit more versatile, same good result

.
@someguyinwaterloo,
in order to help you and if you want more detailed info, you need to do the same for us

.
I see it is your first post, have you made functional backups before? and is it only STL that is causing you problems? Just to be sure we are chasing the proper issue, and that it is not extraction from a 47dj, bitsetting, incompatible burner... if that is your first backup I suggest you start with some of the tutorial
here,
here or
here.
If it is only STL: What version/drive you have? are you using PC drive like (SH-162C) to extract or X360 Drive? Which software (Xbox Backup Creator, Schtrom, isobuster...)?
Really , I am not trying to make you life though, just want to be sure we are looking for an answer to appropriate problem. As they say, there is nothing more useless than a good solution to the wrong problem (after translation

),
rgds, soso