Math…Again

My seventh grader is very bright but struggles with math. It is so strange because he seems to miss some fairly basic concepts.  He has taken the IOWA test and it showed that math was clearly his weak subject.  That has always been the case for him but I am getting to think it is a comprehension issue.  Any thoughts on whether I should have him tested to determine if it is a learning issue or why type of tests?

Thanks, Rhonda