File "_none_", line 1: Error: Required module '<>' is unavailable - makefile

Question

The make file has been executed, there is no bug reporting from each file. However, in terminal, I received:
File "_none_", line 1:
Error: Required module `Prettyprint' is unavailable
The Prettyprint.ml is one of my files. What does this error report mean? Thank you for your help.
First edit:
My makefile looks like:
#echo "# Lexer & Parser:"
ocamlc -g -c parser.mli lexer.ml parser.ml
#echo "# mainfile"
ocamlc -g -c TransitionalSemantics.ml
ocamlc -g -o main str.cma AbstractSyntax.cmo
TransitionalSemantics.cmo Prettyprint.cmo StaticSemantics.cmo
lexer.cmo parser.cmo
In my terminal, the error report begins at:
ocamlc -g -o main str.cma AbstractSyntax.cmo
TransitionalSemantics.cmo Prettyprint.cmo StaticSemantics.cmo
lexer.cmo parser.cmo
File "_none_", line 1:
Error: Required module `Prettyprint' is unavailable
make: *** [all] Error 2

Answer 1

Object files must be linked in an order compatible with their dependency digraph: if one of your module depends on the Prettyprint module, it must be linked after prettyprint.cmo.
Starting with 4.13, the error message is more informative and looks like
File "_none_", line 1:
Error: Wrong link order: B depends on A, B depends on A

Answer 2

You should show exactly what you did to get this error. Otherwise we have to guess :-)
The File "_none_" part means that you're typing in the toplevel so there's no file per se.
The Error part means that the toplevel can't locate your module named Prettyprint. Possibly you need to load it before you do whatever else you did:
# #load "prettyprint.cmo"
(The first # here is the toplevel prompt. The second one is something you should actually type.)
If you expand your question to include more details you will possibly get a more helpful answer.