Instrumentation Failure error when generating coverage report for model containing S-function

I'm using an S-function in my model and looking to generate a coverage report. When I proceed to generate the report, I see the following error message:

ERROR: <S-function file name>: File not included in Coverage Analysis due to instrumentation failure

Why do I get this error? 

Answer 1

[MathWorks Support Team]

In the S-function source code, you may have declared a method without specifying a return type. The compiler used by the coverage report has more stringent checks than the one used to build the S-function, thus resulting in the coverage analysis failing to include the S-function in the report.

In general, if you see a similar error while attempting to include S-functions in a coverage report, please verify the S-function source code and ensure it is free of syntax and compiler errors.