Thanks for sending that Skyline document.
The problem is that you have two separate molecules ("Melatonin" and "Melatonin d4"), instead of what you are supposed to have is one molecule with both a heavy and light precursor under it.
Here is a transition list which you can copy and paste into Skyline which will give you a single molecule (named "NewMelatonin") which will have a heavy and light precursor under it:
|Molecule List Name||Molecule Name||Molecular Formula||Precursor Adduct||Precursor Mz||Precursor Charge||Explicit Collision Energy||Product Mz||Product Charge||Product Adduct
After I do that, I do end up with a calibration curve, but the slope of the calibration curve is negative, which either means that the Analyte Concentrations that you have set on your Replicates are wrong, or maybe the real normalization method was supposed to be "Ratio to Light". I could not figure out how to make your calibration curve look normal, so you might have to ask us some more questions.
By the way, if you wanted to set the normalization method to "Ratio to Light", you would have to first go to "Settings > Molecule Settings > Labels" and check the checkbox next to "Light" and uncheck the box next to "Heavy" so that Light becomes the internal standard. After that, you will be able to choose "Ratio to Heavy" as the normalization method at "Settings > Molecule Settings > Quantification".