Compare problem

My test code is:

{(set: $target="12")
(set: $current="$num1"+"$num2")
(set: $num1 = "1")
(set: $num2 = "2")
(set: $test = "12")

$target = $current?
(if: $target is $current)[
YES]
(else:)[NO]
<br>

$target = $test?
(if: $target is $test)[
YES]
(else:)[NO]
}

Result:
12 = 12 ? NO
12 = 12 ? YES

Debug says:
12 $target = 1 $num1 2 $num2 $current
12 $target = 12 $test

soooo... Problem is obvious. But how can I solve it?