Error in GATK4 MUTECT2

Hello
I am using RNASeq somatic mutations calls, using GATK
I got this error in somatic mutation using GATK4 Mutect::

 BAM header sample names [S1]does not contain given tumor sample name S1

This is how I assigned read groups and sample names::

 S1.dedupped.bam:
 java -Dlog4j.configurationFile="log4j2.xml" -jar ${PICARD}/picard.jar AddOrReplaceReadGroups
 I=${WHERE}/Aligned.out.sam O=${WHERE}/rg_added_sorted.bam \
 SO=coordinate RGID="@E00461_116_EM170602261_1" RGLB=S1_S13 RGPL=ILLUMINA
 RGPU="@E00461_116_EM170602261_1.S1_S13" RGSM=S1

And this is the command that throw the error::

   S1.vcf.gz: S1.bam
   ${GATK4}/gatk Mutect2 \
   -R ${hg38}.fasta \
    -I S1.bam \
    -tumor S1 \
    -O S1_pon.vcf.gz

However 'S1' doesn't show in my S1.bam