MAMP doesn't like multisite-setup (config ok, but themes not found)

Hi there.

I still decided to switch over my sites to multisite-layout.
I've a server running debian and a local mac running osX (MAMP Pro).

On debian my multisite-layout is working well. All works perfect.
On MAMP it didn't work.

my layout on Debain is:

sites/all/modules/drupal-contrib/.. (many opt. modules)
sites/mydomain.com/themes/.. (my real domain theme)

-- this works like a charme

now I copied that into my MAMP htdocs and only changed domain name for testing

sites/all/modules/drupal-contrib/.. (many opt. modules)
sites/mydomain.local/themes/.. (my local domain theme)

-- nothing really displayed, only 1-2 drupal headers in html sourcecode

now I moved my opt. modules directly in /sites/all/modules

sites/all/modules/.. (many modules NOW DIRECTLY here)
sites/mydomain.com/themes/.. (my domain theme)

-- and now, some more entries are in html sourcecode
It seems on MAMP drupal isn't able to have a look into subdir 'drupal-contrib' ??

Also: theme never get loaded from "sites/mydomain.local/themes/" on MAMP. On Debian this works.
When I copied a theme from "sites/mydomain.local/themes/" into /themes it gets loaded.

Very strange or? I activated same parameters to VirtualHost like on Debian. But it seems MAMP does
not like my multiside-config.

somebody here who can help me to track this issue?
would be really nice of you :=)

thx and best greetz
melchior