And the strongest bands are between 1700-1800 cm-1, while yours are 1600-1700. But just a caution - in ATR, the sample penetration is proportional to the wavelength, therefore is less for high frequencies. Thus, compared to transmission spectra (like the Sigma one), CH stretching bands in ATR are weaker compared to lower frequency bands. But I agree that you ought to see something in your spectrum if those methyl groups are there.