Baseline date not calculating correctly.

When customer processing an invoice the due date isn’t calculating correctly based on the invoice date. See screen shot below. The invoice is dated 01/17/2014 and the terms for this vendor is Net 30. The baseline date should be 02/16/2014 (30 days added to the invoice date). The due date is based on the baseline date. This is causing invoices to be paid to soon. 

Pls Advise.

Thank you

Femmy