Bash script, check numeric variable in in range - bash

Question

This is my script:
#!/bin/bash
JOB_NUM=4
function checkJobNumber() {
if (( $JOB_NUM < 1 || $JOB_NUM > 16 )); then
echo "pass"
fi
}
...
checkJobNumber
...
When I try to launch the script I get the message:
./script.sh line 49: ((: < 1 || > 16 : syntax error: operand expected (error token is "< 1 || > 16 ")
(Please notice the spaces in the error message)
I really don't understand what the problem is. If I do the evaluation manually at the command line, it works.
Also, I tried different evaluations like if [[ "$JOB_NUM" -lt 1 -o "$JOB_NUM" gt 16 ]];... still no success.

Answer 1

UPDATE: As suggested I made few more attempts in the rest of the code outside the function call, and I found the problem.
My variables declaration was actually indented this way:
JOB_NUM= 4
THREAD_NUM= 8
.....
VERY_LONG_VAR_NAME= 3
and apparently this hoses the evaulation. BAH! It always worked for me before, so why doesn’t it now?
If I delete the white spaces, the evaluation works:
JOB_NUM=4
THREAD_NUM=8
....
VERY_LONG_VAR_NAME=3
OK I officially hate bash . . . sigh :(

Answer 2

this will work fine
#!/bin/bash
JOB_NUM=7
function checkJobNumber() {
if [ $JOB_NUM -lt 0 ] || [ $JOB_NUM -gt 16 ] ; then
echo "true"
else
echo "false"
fi
}
checkJobNumber
And if you want to check variable during tests you can write in your bash :
set -u
this will generate a message like "JOB_NUM: unbound variable" if variable is not well set