hi robert - - i think I found the issue.....

the problem is not in the use of the bracket, but rather, that an empty set (taking the 0th element of the empty set) is leading to the error.  

If I add to the where class, 'where runid='201' and HbA1cMissing not like '1', I don't see an error.

Thank you for prompting me to take a closer look at the error.