Remove reversed items from the report

Good afternoon.
Please tell me how to write the encoding in the sq report correctly, it seems that I wrote everything according to the rules, but swears at see below.
I added the mseg table to the field groups, pulled all the fields into alv, the fields come out correctly, but when checking the encoding, the fields do not determine why what else needs to be done?
Encoding

clear: smbln, sjahr, smblp.

select single mblnr mjahr zeile
from mseg
into (smbln, sjahr, smblp)
where smbln = mseg-mblnr
and sjahr = mseg-mjahr
and smblp = mseg-zeile.

check smbln is initial.
check mseg-smbln is initial.