Can't use "[url]" in a string in VB4 only?

[BirdOPrey5]

I'm trying to put some bb code in a variable in a plugin... in VB3 I can use:

$mystr = "[url]";

but in vb4 this kills the code... I have no idea why...

$mystr = "[]";

works fine, but with "[url]" execution stops.

--------------- Added [DATE]1295053853[/DATE] at [TIME]1295053853[/TIME] ---------------

Update- OK that wasn't causing the issue, it was using it later in a string replace that is/was...

THIS doesn't work:

$bop_text = str_replace ("{XXX}" , "[url]" , $bop5_text);

Still don't know why...

--------------- Added [DATE]1295055328[/DATE] at [TIME]1295055328[/TIME] ---------------

UPDATE AGAIN... ok it's not the string replace either... what's killing it is when I try to make a new thread with [url] bb code in the pagetext... but I have the same code on VB3 and it works.