Calling CNV using bcftools

Hi,
I used VarScan2 to call variants from whole exome sequencing data. The vcf file output looks like this:

#CHROM  POS ID  REF ALT QUAL    FILTER  INFO    FORMAT  NORMAL  TUMOR
chr1    972251  .   A   AC  .   PASS    DP=173;SOMATIC;SS=2;SSC=75;GPV=1;SPV=2.5611e-08 GT:GQ:DP:RD:AD:FREQ:DP4 0/0:.:65:63:0:0%:36,27,0,0  0/1:.:108:74:33:30.84%:46,28,18,15

I ran this command of bcftools:

bcftools cnv -c NORMAL -s TUMOR -o outdir/ -p 0 samples_concated.vcf

to get copy number variations, but it returned empty files.
Can anyone help me to fix it? Is there any wrong with my vcf file or with my command?
Than you!