issue getting dates on form + adding to database

[Kat Mac]

Hi

I have created a form with a few date fields on it.

acord_date
eff_date
exp_date

When I enter in a date and then click the submit button, the dates
are displaying as 0000-00-00 no matter what date I enter on form.

Example of date input field:
<input type="text" name="App_Date" size=15 maxlength=20>

Here is my php code:
$dApp_Date = $_POST["App_Date"];

When I created the table, here is how I added in the date fields:
hdr_app_date DATE DEFAULT NULL,

I can't figure out what I have done wrong.