ffeditc_unicode[dot]exe has stopped working?

After some time I have attempted to create a carriage - albeit an amended one - and it has exported to MSTS OK. However when I attempt to UNCOMPRESS the associated S file in Shape File Manager an error message pops up as noted in the title! All of the existing S files uncompress fine!
Can anyone suggest what error might lie within the exported S file that might cause this error?

Don't compress in TSM - you probably will need to rename the ace files anyway.

I occasionaly get errors decompressing in SFM. Usually Polymaster will do it or try Route Riter.

Both Polymaster and Route Riter won't uncompress this file. The error messages are as follows when using SFM:-

and

when I click on Close Programme.
I've been back to the TSM folder and checked but it would appear that there must be something wrong with the actual TSM work?

I came across a similar problem on UKTS HERE, in which it was suggested that using the "Fix Bad .s file format" button in the Misc. Options tab of Route Riter might provide a solution.

This too failed so it would appear that I need to go back to the start and rebuild the amended carriage!

I rebuilt the model from the kit of parts that make it up, exported it and this time the Compress/Uncompress routine in SFM worked! Obviously I did something wrong but for the life of me I can't see what!