TOPIC: Problem with custom checkboxes

I\'ve defined 2 checkbox custom fields: one has 9 options, the other is for a \"yes/no\" option.

When the PayPal form displays, I get the following error:

Warning: implode() [function.implode]: Invalid arguments passed in D:\\wamp\\www\\pmsfoundation\\components\\com_dtdonate\\dtdonate.php on line 5837

The errors seem to be specific to the checkbox fields; if I unpublish them, no error occurs.

Note that both custom fields displayed OK on the previous page; only the PayPal submission page gives the errors.

Please advise- I am building this site behind a firewall for approval before turning it live. I hacked the code to get a var_dump of $rowCustoms, which appears on the attached screenshot.