add to cart in category page and categories

[f4uf4me]

when i overrides template of virtuemart1.9.8.RC2d_extract_first.zip, i need a add to cart on category page, not product detail page, but something wrong, it can show, but when i use firebug to inspect this, i find a error like this:
addtocartproduct Notice: Undefined property: VirtuemartViewCategory::$product in C:\Apache2\htdocs\namphongshop\templates\namphong\html\com_virtuemart\category\default.php on line 95 Call Stack: 0.0007 355136 1. {main}() C:\Apache2\htdocs\namphongshop\index.php:0 0.0818 5555896 2. JSite->dispatch() C:\Apache2\htdocs\namphongshop\index.php:43 0.0876 5910608 3. ........
how can't i fix it, i'm a beginer with php, i am learning it, hope help to become a development

[Milbo]

I think the fix is atm to disable SEO/SEF for joomla.

is this problem on j1.5 or j1.7?