[Vivi Ornitier]

afterlab: there shouldn't be any negative number. there's an if statement that compares your points to the the item you want to buy. If you don't have enough points you get am error message. (you actually shouldn't even see that at all, because there's no link if the item costs more than you have.

my conclusion is that you did something wrong when editing itemshop.php

watch for
if($points >=$value) {
that if statement checks checks your points. if your have more of equal to the points of the item you want to buy it will continue. if not, it will send you to the error page:
header ("Location: itemshop.php?action=error&why=points");

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tsk it was the old version again, here is he fully fixed version.
ouch. forgot template. :?:

...
working on sell function.