Mailchimp List Subscription with comments plus error

I have comments plus and MC List subscription installed and when commenting and checking the box to subscribe to newsletter, I get the following errors:

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'wdcp_mcls_mailchimp_signup' not found or invalid function name in .../wp-includes/plugin.php on line 406

Warning: Cannot modify header information - headers already sent by (output started at .../wp-includes/plugin.php:406) in .../wp-includes/comment.php on line 619

Warning: Cannot modify header information - headers already sent by (output started at .../wp-includes/plugin.php:406) in ...wp-includes/comment.php on line 620

Warning: Cannot modify header information - headers already sent {...} on line 621

Warning: Cannot modify header information - headers already sent by (output started at .../wp-includes/plugin.php:406) in .../wp-includes/pluggable.php on line 876