What do you mean with 'data needs to be read only'? If a user has edit rights on the data, you can't make it read only through a report.

The user will at least need access to the data. Also: check the report_view acl's. 

But the report should be there if you shared it, because then it would open the report, saying that there is no access to the data. How did you share it? What roles does the user have?