Invisiprim Problems

Hi,

I have just made a set of heeled shoes for myself. They are not stillettos, just heeled pumps.
Obviously, because of the heel and the fact that it is a prim shoe, I need to make an invisiprim to stop my foot showing through the heel.
I have worn the foot shape with the transparent texture and have created an invisiprim and linked it to the shoe in the correct place.

my problem is that I think there is a problem with the script or something. I have the invisprim script (I actually have 2, v1a and v1b). I put this into the contents of the right prim and nothing happened.
I thought the prim was supposed to disappear but it didn't. I thought it was a minor glitch so i textured the prim with the full transparent texture and tried to wear the shoe.
No dice. My foot still shows through the heel.
This thing just doesn't want to work. I have tried using both scripts, i have tested them in other prims and it won't work.
Does anyone have any idea what I could do to make this work? I really like these shoes and want to be able to fix this.

Thanks

xxClairexx

PS. I'm not sure if this is in the right place. It may need to be in the scripting tips but i figured since i was building it may be something that needs to be in here. I don't want to post twice because that would just tick people off so I put it in here.
Thanks

are you in an area that allows scripts?

you can test that by throwing a line in after state entry (or in front of the llSetTexture Line ) that read
llOwnerSay( "I work" );

if you don't see "I work" pop up in chat, something is wrong

I'm pretty sure I was. I was working while on my workspace buster (a scripted box which rezzes a panel in the sky for you to stand and work.) It let me sit on it and it rezzed fine. There were quite a few scripted objects there as well.
I'll try in another sandbox later tonight though, just to check.

also just offhand, make sure that the prim you are using doesn't specify any transparency on the texture tab (it should read 0)