Have you checked your file?
Photoshop (.psd) or vector files work best for screen printing.
Most art programs (including procreate, ibis paint, clip studio, etc) can be exported as a .psd file.
Size: Design should fit between 12.5 inches wide x 14.5 inches tall at 300 dpi (or higher).
The example below shows the correct file size and resolution at 300dpi.
Ideally make sure your color layers are separated. For halftone images, place the areas that need to be halftoned on a separate layer.
The example below shows how the solid black and red ink layers are separated, and the soft brushes/halftones are also separated on their own layers.
