I have a vcf file, I annotate that file whit annovar and in the resulting txt file I have this row

chr7    140453136   140453137     AC   TT  exonic   BRAF    .     nonframeshift substitution              BRAF:NM_004333:exon15:c.1798_1799AA:p.V600K

If I convert the txt file in maf using annovarToMaf function of maftools package I obtain NA as Variant_Classification. What is instead the correct classification in maf files for this kind of variants?