[Vcftools-help] Problem with bcftools merge

[Baes C. <Chr...@qu...>]

Hello,
I'm trying to merge a few bovine sequences together and am having some difficulties.
The goal is to merge 38 single-sample .vcf files (called using freebayes) into one .vcf file, but I'm starting with only two of these files.

I've bgzipped and tabix-indexed all .vcf files, but I can't seem to get bcftools to work properly.

My input lines are as follows:

/qualstore03/data_projekte/projekte/sequence/linuxBin/bcftools merge \
--merge none \
/qualstore03/data_tmp/projekte/Sequence/Unzipped_G2F/BSW/BSWCHEM120000771198_BTA1.vcf.gz \
/qualstore03/data_tmp/projekte/Sequence/Unzipped_G2F/BSW/BSWDEUM000813034326_BTA1.vcf.gz \
--output-type v


But I only get the header and the following error message:
bcftools: vcfmerge.c:1041: merge_info: Assertion `idx>=0' failed.
Aborted (core dumped)

On another chromosome, I got the first two positions which occured in each .vcf file privately, but I got the same error message as above before the first merged position was included.

Perhaps there is something wrong with my index files, but I'm not sure what that could be.
I indexed my files using the following command: tabix -p vcf /qualstore03/data_tmp/projekte/Sequence/Unzipped_G2F/BSW/${animal}_BTA${Chr}.vcf.gz

I would really appreciate any help.

Thanks in advance,
Chris