[wp-hackers] Problems with shortcode function in plugin

[andré renaut]

http://codex.wordpress.org/Shortcode_API

"When the_content is displayed, the shortcode API will parse any registered
shortcodes such as "[my-shortcode]", separate and parse the attributes and
content, if any, and pass them the corresponding shorcode handler function.
Any string returned by the shortcode handler will be inserted into the post
body in place of the shortcode itself. "

so no echo just retrieve a string !