Undefined appearing in Add to Cart number

[myiHub]

Hi
We have created a site using Joomla! 2.5.8 and Virtuemart 2.0.16 that sells school uniforms.  The client required variants of 'Size' and 'Colour' to be included and a compulsory selection of same or the user could not proceed to checkout.  No stock control was required and there are only a few variations in pricing depending on size chosen.  We have created child products for size and colour using the Custom Field Type; Cart Variant - which is Cart Attribute.  We used the Plug in called 'VM - Custom, Stockable Variants'.  Everything appears to be working fine other than one little bug. 
A user can select a size or colour variant and the price increase/decreases no problem.  However we are getting an 'unefined' on number in the add to cart.  You can only achieve an item count of '1' if you hit the '-' sign as opposed to the '+' sign.  We have tested adding '1' to the Product Status/Minimum Purchase Quantity but the error still occurs.  Any help on this would be appreciated.  You can see it occurring here:  http://184.154.232.20/~cac02861/index.php/cac-shop/uniform-shop/dresses/dress-yrs-1-6-detail#.UOzRum-ceSo

Thanks a bunch

[muguet]

I have the same problem  http://test.ankle-biters.com/index.php/products/party-dresses/red-origami-detail
BUT....I see you solved yours? Or at least,....I don't see any "und" in the Add to Cart??

[myiHub]

Hi yes, an Elance developer fixed it for us at a cost of $100 Aud.  He explained it was JSON and Jquery and AJAX and SESSION issues.  Happy to provide you with his contact details if you inbox me.