Companies do not use all available financial metrics (XBRL tag/TID) in the system. Hence, "no data" outputs are expected on your reports, particularly if "comparing companies".
XBRLAnalyst offers three options on how "no data" output will be returned to Excel. To customize it, click "Settings", "No Data Output", and choose from options: NA, Blank or Zero. All functions and reports will generally follow this setting.