Bert French

Hi at all, 25 years ago I used a CZ 5000, I sold it in 2006. Now, I got a CZ 3000, and I'm happy to have got him back! He has brand-new batteries on bottom, but if I write something to memory the sounds are lost when powering the synth off. He receives sysex data without problems. Does someone know why the memory is lost after powering off? Thank you in advance and groovy greetings! BERT