I want to do a for loop around the picard tool, AddOrReplaceReadGroups, but I get an error that has something to do with my input and output paths (I think). Can someone tell me where I went wrong with this:

# pwd: /Users/phylofun/Downloads/project

for i in mapping/*-pe.bam;
do
    java -jar ~/miniconda2/jar/AddOrReplaceReadGroups.jar \
    I="$i" \
    SORT_ORDER=coordinate \
    RGPL=illumina \
    RGPU=D109LACXX \
    RGLB=Lib1 \
    RGID="${i%-pe.bam}" \
    RGSM="${i%-pe.bam}" \
    VALIDATION_STRINGENCY=LENIENT \
    O=picard/"${i%-pe.bam}-pe-RG.bam"
done

error: Cannot write file: /Users/phylofun/Downloads/project/picard/mapping/sample1-pe-RG.bam. Neither file nor parent directory exist.