ValueError: Substring not Found

[amootta]

Hi all,
I am trying to run NGSCheckMate on paired normal-tumour samples. It seems to be running the samtools mpileup fine, and producing the appropriate vcf files. However, I received this error:
Traceback (most recent call last):
File "ncm.py", line 1440, in
run_mpileup()
File "ncm.py", line 1206, in run_mpileup
tag = filename[-1][0:filename[-1].rindex(".")]
ValueError: substring not found

could you please let me know how I could fix this? Thanks very much