error convert gtf to bed

Hi, I have been trying to convert the mm10 GTF to BED but the get the following error:

invalid gffGroup detected on line: chr1_GL456212_random mm10_refGene exon 31027 32140 0.000000 - . gene_id “NM_001372515”; transcript_id “NM_001372515”;
GFF/GTF group NM_001372515 on chr1-, this line is on chr1_GL456212_random-, all group members must be on same seq and strand

Could anyone advice?
Thanks
alessandro