Custom variable as check_snmp threshold


i’m trying to use check snmp to get the number of ap’s connected to a controller and warn if any are down and critical if under 1 and over 16

in the host file i set __totalap as number

__totalap 7

check_snmp -H $HOSTADDRESS$ -o oid -C snmpcommunity -P2c -w $_HOST_totalap$:$_HOST_totalap$ -c 1:16

i can replace the totalap variable with the numbers and this works correctly but when i use the variables i get invalid warning threshold - $:$
i get the same if i place the variables in quotations

if i place single quotes around the variables i get invalid warning thresholds - $_HOST_totalap$:$_HOST_totalap$

is there a different way i should type the variable in the check command or am i misunderstanding the use of these variables.