Allow owner to get rewarded

[Chaos77777]

Lol, well I thought I could figure it out for myself. I guess not :(
I'm wanting it to reward the owner 1 percent of the cost of the adopt.
I tried a bunch of different variations of
$owner->changecash($mysidia->adopt->cost);


But it keeps saying it's a non numeric value.

I tried using
$owner->changecash($mysidia->adopt->cost * .01);
It doesn't give me any errors, but it doesn't actually increase the money.

$owner->changecash(1);
This one above works just fine, but I set up a rarity system. (I got lucky making it work) and want people who own rarer adopts get a better reward. Any clue?

I looked around in pound and poundview to see how it works in there, since that also uses a percentage system, but I'm not having any luck using any of those