sql not working

I created a few tables in my main wordpress database…

table names:

cards
scards

I put a plugin that lets me use php in pages, I use it in my other wordpress sites, very succesfully… but in this new website I’m working on, I cannot get the SQL to work right.

Here is what I am trying to do:

[php] // This opens a PHP Tag like <?php would...

global $wpdb;

$_openm = $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM cards" ) );
$_amtClosed = $wpdb->get_var( $wpdb->prepare( "SUM(f1) from scards" ) );

[/php]

Content... content... content... then I use the variables...
Open cards ([php] echo $_openm; [/php])
Closed cards total funds ([php] echo $_amtClosed; [/php])
more content...

But the variables are blank on the page output.

I have tested the php tag like this:

[php] echo "Hello newbie";[/php]
and that does output that, so it is executing the php.

Can you tell me what I did wrong? I even tried to put those variables as global in case it was not remembering them after I closed the first php tag…

still nothing.