THIS_SCRIPT in template needs help

[hazem_aliraqi]

hello guys

I wonder How to use THIS_SCRIPT


the template i need to use the condition is headinclude

this condition

PHP Code:

<vb:if condition="THIS_SCRIPT == 'showthread' OR THIS_SCRIPT == 'threads'">
code
 </vb:if> 


its in all the page


i need the condition in the first post only

i tried this but not work

PHP Code:

<vb:if condition="$post['isfirstshown'] && $thread['firstpostid']==$post['postid']">
code
 </vb:if> 


also this

PHP Code:

<vb:if condition="(THIS_SCRIPT == showthread) AND ($post[postcount] == '1')">
code
 </vb:if> 


and this

PHP Code:

<vb:if condition="THIS_SCRIPT == 'showthread' AND  $thread['firstpostid']==$post['postid']">
code
 </vb:if> 


all this not work in headinclude template

so that i need help to make my code work in first post only