[SOLVED] Embedded Flash not visible

WP 3.0.4.
Atahualpa 3.6.1.
Recently moved from 'Bytes for All' theme to 'Atahualpa 3.6.1'
Regularly we publish a post with an embedded flash slide show from photos on Picasa.
The embed code we get from the Picasa account. Of course we put the embed code in the WP HTML post editor. In the WYSIWYG post editor, the yellow rectangle is visible.
In the old theme no problems. In the Atahualpa theme however the slideshow is not visible after publishing.
There is an empty space in the post at the spot where the slide show is supposed to be. Right clicking on this open space gives the opportunity to change the properties of the flash player. However no slide show visible.
Disabling all plugins did not make any difference.
In earlier posts with an embedded flash slideshow, the slideshow is still visible.
We have a small community on this members only blog and this embed feature is very important to us.
We have limited knowledge of HTML