Why won't my Mazda millenia transmission shift?

If your Mazda Millenia transmission won't shift, it could be due to several reasons, including low Transmission Fluid levels, a faulty transmission control module, or worn-out internal components. Additionally, issues with the shift linkage or a malfunctioning throttle position sensor may be contributing factors. It's advisable to check the fluid level and condition first, and if that appears normal, consider consulting a professional mechanic for a thorough diagnosis.