If test problem

Hey guys....

I'm having a problem with a script that I wrote. The problem that I'm having is with the 'if' test. Here's the code...

Code:

---

echo "Enter data."
read variable
if [-z $variable]
then
        echo "Please restart script and enter variable when asked."
        exit
else
        ...else stuff...
fi

---

I get an error that looks like this:

Code:

---

./fw-calc: [-z: not found

---

I've tried several different ways and all come out with basically the same result. I want the logic to read as follows...

Code:

---

if variable is null
then
    ...variable null code...
else
    ...variable NOT null code...
fi

---

Any help would be appreciated. Thanks.

Oh, this is in Solaris 8 BTW if that helps.