Hey,
Im trying to build a skyline library with my maxquant search. All my other files have been fine, but for some reason whenever I try to use the files where the N-terminus was modified to have a heavy acetyl group, skyline says there is no matching mod for the N-terminal heavy acetyl group. The modifications file works fine for my other runs. It also appears that the heavy acetyl label on lysine residues is ok too. It only appears to have an issue with the N-terminus modification.
I will include a screenshot of the error message, as well as one of the area of the modifications file where this mod is listed.

Thanks for your help
David