Hi can anyone help?

I have created a user form that has text and combobox's on it, the user enters data and a start date in a textbox 3 and a finish date in textbox 4. Once the form is completed they clck submit and it fills in the next empty row with the data, Id No - name - start date - finishdate etc, problem is some enter dates i.e 01.01.2014 or 01/01/2014or 1.1.14 so I need a madatory date entery calander that replaces the two text box's on the user form and fills in the cells that the textbox's did?

thanks

Huffers