Renaming Columns in Power Query Gives Error

Hello!

 I am working with a large dataset, and need to organize the sales summary across different company divisions. In our database we use acronyms like "RW" for "Retail West" divisions. I want to make the report very user friendly, so I decided to replace all of these short acronyms with their actual names. This was going well ( I was using replace all in power query editor ) until I ran into this error part-way through my query.  The replace statements caused no issue, until I added this final one. I am working with data off of a IBM DB2 Database.

I attached 3 photos of: the query before the error, the error itself, and the query after the error. I think the error is with my dataset, and not quite a power bi issue, But, do you guys have any idea what may have caused this? or if there is another way to change the replace the names of these values? at least for those who view the report.Photo 1, before the error (working Query)After I added another "replace value"the advanced query editor, after error was given

This last photo is a basic example of how I use these in a table. Some are still unchaged ("I", "MT"...) but others are replaced.