size of a variable

why wont this work?

if (sizeof($item) <= 1) {
echo "you are too small";

} elseif (sizeof($item) >= 14) {
echo "you are too big";

} else {
echo ("you are just right");
}

I also tired count() and set sizeof($item) to a variable first and put the variable against the < and >

The "$item" is a search word from a form, the form works great but the above will only ever output "you are to small"

[edit] If I do $the_length = sizeof($item); echo $the_length; the output is 1
I think it was the manual says sizeof is for variables and arrays but input from users say it's only for arrays (I'm using a variable)[/edit]