Max Carranza

Hi there! First time posting on here, and i am looking for some assistance. I have noticed that i have lost reverse altogether, however, with the exception of 3rd gear, it seems like the transmission is working just fine. Could somebody explain the root cause of this? I used the OBDI and it gave me 26 flashes in return. According to a mercedes troublecode website, it says it has something to do with the upshift delay switcher solenoid. However, this doesn't seem to explain why exactly i can't go into reverse if it is related to shifting up. Thanks in advance! Appreciate any and all help on this one.