This won't work. Shortcodes cannot be executed in the php code.
Check to see if that plugin has the option to render on specific hooks.

You can also ask the plugin developer if you can dynamically pass arguments in the plugin.

Hello Krikor, thanks for the reply, I cntacted the plugin developer.

Meantime I ve another question for you.

is it possible to use sig pro with a slideshow interface ?

@Ali Can

Simple Image Gallery PRO is used to create galleries not slideshows. However some of the popup engines include a very simple slideshow functionality. You can take a look at the demo page at demo.joomlaworks.net/simple-image-gallery-pro to see what Simple Image Gallery PRO can do.

any chance to {loadposition} in item.php ??

Found a better way.

extrafields can execute plugin codes. so I put my plugin code ( in my case widgetkit ) in a extrafield. and call it in IMG section of item.php, I put a if else statements so if the item has slideshow extrafield it shows, else it brings original item image.