Error in PHP script

Hi,

Just moved to Hostgator from Dreamhost.

PHP script that worked fine on DH, now errors. I changed register_globals from ON to OFF to fix one error, but now get another:

Getting 'Invalid argument supplied for foreach() in ...' in the following code.
I'm a complete PHP newbie and need some help, please:

<?
foreach( $previously_imported_files as $pi_file )
{
?>
<div style="color:#333333"> cp -f <?=shell_escaping($pi_file)?>
<?=str_replace('filesystem','filesystem_imported', shell_escaping($pi_file))?>; <br>
rm -f <?=shell_escaping($pi_file)?>; <br>
</div>
<?}?>

Any ideas?

Thanks.