bash associative array value empty using variable key, based on lookup file - bash

Question

I need to lookup data from a lookup file. I am using bash ver 4.1.2 on rhel.
Lookup data (ip_lookup.txt)
1.1.1.1=server A
2.2.2.2=server B
.. and so on
I iterate list from a file (aggregated from access.log) and need to add information from the lookup file.
iterated list (service.txt)
1234 service_a
324 service_b
34 service_c
access.log with x_http_forwarder info
service_a 200 1.1.1.1
service_a 200 1.1.1.1
service_a 200 2.2.2.2
service_b 200 1.1.1.1
service_c 200 2.2.2.2
So the code I made was this:
# import lookup file into bash array
declare -A ary
while IFS== read -r key value; do
ary[$key]=$value
done < "ip_lookup.txt"
# then I nested iterate from list service and access.log
# list service and its caller
while IFS=$'\t' read -r -a line
do
echo -e "${line[0]}\t${line[1]}"
cat "access.log" |
tr -d \" |
sed "s/?wsdl.$PARTITION_COLUMN.\t/\t/g" |
sed '/^[[:space:]]*$/d' |
sed "s/?WSDL.$PARTITION_COLUMN.\t/\t/g" |
grep ${line[1]} |
awk '{ seen[$3] += $1 } END { for (i in seen) print seen[i],i }' |
sort -nr |
sed 's/ /\t/g' |
head -n 2 > "ip_list.txt"
while IFS=$'\t' read -r -a line
do
# the problem lie in this block <<<<<<<<<<<<<<<<<<<
echo -e "> ${line[1]} \t\t ${line[0]} \t\t ${ary[${line[1]}]}"
# it only returns var line 1 and line 0. While lookup var ${ary[${line[1]}] is empty
# fyi, ${line[1]} returns 1.1.1.1 or 2.2.2.2 (on each iteration)
fi
done < "ip_list.txt"
done < "service.txt"
Let me highlight the problem:
ip=${line[1]}
echo $ip #it returns IP such as 1.1.1.1
echo ${ary['1.1.1.1']} # it returns server A
# but if I call the key using variable, it won't work. I've tried some combination but it works nothing.
echo ${ary[$ip]} # it returns nothing
echo ${ary[${line[1]}]} # it returns nothing
echo ${ary[${!line[1]}]} # it returns nothing
Any idea how to return the value using the key variable in bash associative array?
feel free to ask the detail.