This error means that something is being called as a module (or package) in Maple that isn't a module.
Error, `foo` does not evaluate to a module
This error can also occur if
:- is being used incorrectly. In general
:- should only be used to call a function from (or retrieve a constant that is exported by) a package (or module).
Sometimes this error can be received when it isn't obvious where the call to the 'module' is happening.
If you receive this error when starting Maple or when calling a built in Maple function please contact Maplesoft Technical Support at email@example.com. It's possible that your installation of Maple is corrupt and you may need to download Maple from a new download link.