Closed Thread Notification show on Private Message?

[v123shine]

vb: 3.8.x
Template: postbit_legacy

I used this conditional to show notification in close thread:
<if condition="$thread[open] == 0"> Notification for close thread </if>

I got a problem, my notification for close thread also show on Private Message.

How to disable notification in Private Message ???

Thank you

--------------- Added 1340154896 at 1340154896 ---------------

I found the solution:

<if condition="THIS_SCRIPT != ''">

Thank you