Bash shell script Nested while loop with IFS

I'm trying to parse a set of csv files using bash shell script the files looks as below:

File1: /tmp/test.txt
key1,key1file.txt
key2,key2file.txt
key3,key3file.txt

Files: /tmp/inter/key1file.txt
abc,cdf,123,456

Files: /tmp/inter/key2file.txt
abc,cdf,123,456

Files: /tmp/inter/key3file.txt
abc,cdf,123,456

I've tried parsing these files using 2 while loops:

while IFS="," read keycol keyfile
do
    while IFS="," read keyval
     do
     echo "inside inner while loop"
     echo "$keycol|$keyval"
    done < "/tmp/inter/$keyfile"
done < /tmp/test.txt

and expecting this code to output

key1,abc
key1,cdf
key1,123
key1,456 and so on...

However, i'm not getting any output when i run this code which indicates the second loop is not being executed. Any pointers in the right direction would be of help. Thanks