When running the following commands in Codebook:
import refinitiv.data as dl
dl.open_session()
df=dl.get_data(['MMM.N', 'APO.N', 'IFC.TO', 'JPM.N', 'PGR.N', 'WRB.N', 'KKR.N'], ['TR.CompanyName', 'AVAIL(TR.Revenue(Period=FQ0).date,TR.Revenue(Period=FI0).date)'], parameters={'NULL':'Blank'})
,dates are not returned for some companies (see screenshot).
Why is this and how can it be corrected?