struct fruit
price dd ?
local db ?
ends

virtual at edx
.banana fruit
end virtual

lea edx,[.banana.price] ;<- ok
mov edx,.banana.price ;<- failed

any idea?

SIB addresses cannot be used like register operand, sorry.
Note that in most cases it would anyway make no sense as it would be "mov edx,edx+some_offset". fasm doesn't bother checking whether the offset it zero (and whether there is no index register, too) to detect the rare case when it could get reduced to be only the register, thus this is like a fasm's limitation. I don't consider it to be very limiting, though.
PS. This limitation also applies to the cases when you write "mov edx,2+edx-2" etc. It's because "2+edx+2" is an expression and simple "edx" is an register - something different from the parsed source point of view (see how the "eqtype" works).

thank you