you have an unmatched single quote somewhere in your file.
Unlike most languages, Prolog has 'atoms', Identifiers that start with lowercase are atoms
i_am_an_atom
but you can also make an atom by enclosing anything i single quotes
'I AM AN ATOM TOO!!!!'
the built in editor can help. load your program and query
?- edit.
the editor will stop coloring at the start of the long atom