Conditional Statement adrotator plugin

I am trying to write a conditional statement for the adrotator plugin so the theme doesn’t break if I have to deactivate the plugin.

Everything I have tried either shows nothing or gives me a t-string error.

Can anyone point me in the right direction?

this is the statement supplied by the plugin
<?php echo getad('bannerad') ?>

this is the lastest attempt at a conditional statement

<?php if(function_exists('adrotator')) :
echo getad('bannerad'); endif; ?>