SAP Query and ABAP code

Good afternoon.

Please tell me how to correctly write the encoding in the sq report, swears at see below. Added the mseg table to the field groups, pulled all the fields into alv, the fields come out correctly, but the fields when checking the encoding does not determine why what else needs to be done?

My task is to delete reversal documents

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.