Traffic Court Issues: Traffic Court Failure to Appear Resulting in a Driver's License Hold

My question involves a FTA from LA County, CA. In February of this year I was granted trial by declaration for my speeding case. I mailed in my check and my statement and waited. On Monday I received a letter saying I had a failure to appear and a license hold. I went to court and was told by a clerk "Sorry the computer says we didn't receive anything so it's not our problem." I've set a court date for late April but I'm freaking out, I'm in the hiring process for a major ambulance company and a failure to appear on my record will ruin me.

Traffic Court Issues: Traffic Court Failure to Appear Resulting in a Driver's License Hold