1999 Saturn SC2 Check engine light, error code reader won't

Hi. My check engine soon light came on yesterday in my 1999 saturn sc2. I took it to shucks and autozone because they have free testing with the code readers. Well at both places the code readers, when plugged into the slot under the dash, failed to read anything. It would start and you could see the lights blinking but no error code or any kind of transmission could be retrieved. Even the workers at both places came out and tried and were stumped as to why my car was not sending a signal to the code reader.

So, what could cause my connection/car to not send any type of communication to these devices? I need to get that light off but can't until I get a code. Is there fuses for that, or whatnot? Could it be shorted somehow? Thanks.