$this->input->post() data and "undefined index"

[eluser]tinawina[/eluser]
When check Aging, Agriculture and Food, Women and then var_dump($this->input->post()) I get this data pertaining to subject:

Code:

["subject"]=> array(3) { [0]=> string(5) "Aging" [1]=> string(20) "Agriculture and Food" [2]=> string(5) "Women" }

I am able to process this just fine and get the data working for me. But if I check any subject checkbox I get that index error message. If I don't check anything I don't see the error.