decimal quantity extension not work at admin page

i have bought Include Decimal Place Value (vqmod) extension.
this extension is used for include decimal values in product quantity field.
it works fine at front end but when i check sales order at admin page it shows integer value for that product.
like if i order 1.5 kg of any product and print its order invoice i found product quantity 1 but billing of 1.5 kg.
how can i setup it at admin page as front page quantity.please help.

try contacting the extension developer