@acer 

Thank you very much!  It's good enough for me.   I have made some backup copies before.  But this file contains my work last night.

I saved the file properly before putting the computer to sleep , but I found my computer  hibernate failed this morning.  When I turned on the computer and opened the file I found out that it was corrupted.  So I suspect that the maple tried to save automatically during hibernation, so something went wrong.

 I've turned off the auto-save of the maple.  And In the future, I will make a backup copy before I hibernate the computer.

Thanks again!

@acer

 EchoModel_V3.zip

Very grateful for your help !