Try with “LBR+” fit options (you’ll get better “agreement” for the last peak).
Then show it to your supervisor, who should easily be able to explain the nonnegligible differences between the fitted peak area and the corresponding histogram integral. 
Try with “LBR+” fit options (you’ll get better “agreement” for the last peak).
Then show it to your supervisor, who should easily be able to explain the nonnegligible differences between the fitted peak area and the corresponding histogram integral.