Data format not on every post

I am having trouble with 2 wp installs…
Both do that only some blogs are with the date they were blogged…
The code for both places are this:
Posted on <?php the_date(”,”,”); ?> at <?php the_time() ?> by <?php the_author() ?>
It works at times and at times it don’t.. I am using them for news on 2 fanpages…
Are the codes wrong or??