Can you send us your Skyline document?
In Skyline, you can use the menu item:
File > Share
to create a .zip file containing your Skyline document and supporting files including extracted chromatograms.
If that .zip file is less than 50MB, you can attach it to this support request.
Otherwise, you can upload it here:
The limit of detection involves looking at the observed peak areas of the blank samples, and figuring out where that would fall on the calibration curve. It sounds like Skyline might not be correctly taking the inverse of the parabola function.