Might help if you told us what program you are using...

Try using Wilcom Tru Sizer and save it to .jef.

I have Embird and have no problem changing.
It could be that the design is too big for the hoop or the hoop measurements doesn't match a Janome hoop size.
Can you set up a hoop size that matches a Janome one and bigger than the design to test?

It may be a later version of pes. Is your Wings up to date?

Try formatting again--for instance, change to .hus and then back to .jef. The only time Ive seen that exact message is in PE Design software when the design is a later "model" than my software. I can change to earlier version w/older Pulse Ambassador---but Brother machine will read it anyway without changing. The Bro machines will read any version. But I like my software version in case I want to 'play around' (ie editing or merging).