Gantry Problem - Layout always back to default

I know this is wpmu forum, but may be someone can help me here. Since i really really confused with rockettheme support. Waiting for an answer can make arrgghhh.

I try to use rockettheme and when i do change a setting of theme layout, i found that what i change in layout tab is not saved. it include if i try to do it in override at layout tab.
When i click a "save" button, it still said that it success to save. But if we back to a layout setting letter, it always back to default.

A problem only happen in layout specific at "positions" and "position count".
"Force Position" working fine and anything in other tab is fine, any changing is save correctly.

I try to capture a traffic and found, if i do change something in layout->positions, a POST request that sent by browser is always same, no mater what i change in layout.

i try using 2 different browser, chrome and firefox.
try also to change a themes from diametric until stratos.
log file is fine. no error found.

WP 3.7.1 (MS)
Gantry 4.0.8 (i also try to up and down a version)
RokCommon 3.1.6 (i also try to up and down a version)

To make sure, I do try to install it in my PC with 2 different installation (MS and single) and both have a same problem.

somebody can help me with this ?

Thank you