Bug in expr***urgent

[salih k]

Hi,
There is a bug iin the expr command and exit status is"51198" some times
"1552"
I have used expr to check whether the variable is numeric
       add_num=`expr $int_num + 1 1>/dev/null 2>&1`
 kms=$?
       # if [ "$?" -ne "0" ]
         if [ "$kms" -ne "0" ]
        then
here $kms returns exit status other than zero even if $int_num is numeric


Please help

Thanks,
Salih