Unsupported mean iterator type query.stringInterruptIterator

Need some assistance. I imported a csv into influx. it uploaded successfully. i tagged 2 items called App and Server. Under App there are multiple Servers and there are also multiple Apps. I can query on Server and i see my graph. i can query on App and it aggregates all the Servers under that app and i can see data. If i try to query App then a Server under App i don’t get any data. Any idea why this is happening ? Also i tried chronograf to see the data, and when i try the same query App then a Server under App i get

*unsupported mean iterator type: query.stringInterruptIterator

what am i doing wrong ?
Thanks again.