Android Question Which background color is used after LoadLayout to panel ?

I have two layouts: main and sub.

In main layout I have mypanel.
In Designer:
for sub I set Activity.color = Transparent
for main I set mypanel.color = Gray

I do
Activity.LoadLayout("main")
mypanel.LoadLayout("sub")

and I don't see Gray for mypanel.
What I should do fix this problem ?