a scritp only goes on my site with 1.3.7 and not on other my site 1.3.8a

[giuly]

hello, a question, a script in php and jscript functions on 1.3.7 zencart, but not on 1.3.8a, the jscript that is a popup doesn't go.

I have to ability something on zen cart 1.3.8a??
Thank you very much