>> something im doing wrong? as others have explained, you are creating out-of-gamut colors in your RGB mode, here's the PROOF: somewhere in the above Granger Chart is your green here is the Photoshop "soft proof" in CMYK mode: as you can see the CMYK space does not contain your green the smaller CMYK print Space (paper and ink technology) simply is not physically capable of reproducing the pretty colorful saturation, gamut and dynamic range of the source or monitor RGB Spaces used in the RGB rainbow of color spectrum example your printer probably wants to run your green as a "spot color" to make you not disappointed in your creation professional and amateur printers alike should make themselves intimately familiar with Photoshop's Soft Proofing and Gamut Warning tools and train their eyes to work within more real-world color gamuts and dynamic ranges for print work
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