Does anybody have any experience programing a Siemens LOGO 12/24 PLC? I have an old unit that wasn't performing as I would like it to. I downloaded the instructions, was able to get into the program mode and delete the old program. I wrote and entered the new program, and it worked just fine, until I turned the power off! When the power was restored, the display says "no program, press esc. Obviously, my just entered program wasn't saved.
According to the instructions, simply exiting the program mode stores any data. I have tried pushing the same buttons that got me into the program mode before exiting and many other variations, but I still can't get the PLC to save my program. I have a feeling I'm missing something simple but just don't see it.
Any ideas?

Thanks
Dave