Looking at the source code of the page,
this is the add to cart form that gets created for one of the items that works:
<td align="left" valign="middle"><form name="teacherslunchbox_21_ATC_14" method="POST" action="/ourlunches2.php">
<p>Quantity:
<input type="text" name="teacherslunchbox_21_Quantity_Add" value="1" size="4" >
<input type="hidden" name="teacherslunchbox_21_ID_Add" value="14" >
<br>
Bread:
<select name="teacherslunchbox_21_Bread_Add">
<option value="Honey Wheat">Honey Wheat</option>
<!-- <option value="Pumpernickel">Pumpernickel</option> -->
<option value="White">White</option>
</select>
</p>
<p>
<input type="image" src="WA_eCart/Images/Pacifica/Btn3_EN_addtocart.gif" border="0" value="Add to Cart" name="teacherslunchbox_21_ATC" >
</p>
</form></td>
This is the add to cart form for an itwem that does not work:
<td align="left" valign="middle"><form name="teacherslunchbox_1_ATC_" method="POST" action="/ourlunches2.php">
<p>Quantity:
<input type="text" name="teacherslunchbox_1_Quantity_Add2" value="1" size="4" >
<input type="hidden" name="teacherslunchbox_1_ID_Add2" value="" >
<br>
Bread:
<select name="teacherslunchbox_1_Bread_Add2">
<option value="Honey Wheat">Honey Wheat</option>
<!-- <option value="Pumpernickel">Pumpernickel</option> -->
<option value="White">White</option>
</select>
</p>
<p>
<input type="image" src="WA_eCart/Images/Pacifica/Btn3_EN_addtocart.gif" border="0" value="Add to Cart" name="teacherslunchbox_1_ATC" > </p>
</form></td>
the main differance is that the one that does not work has a blank value for the ID:
<input type="hidden" name="teacherslunchbox_1_ID_Add2" value="" >
The one that does work has a positive value for the ID:
<input type="hidden" name="teacherslunchbox_21_ID_Add" value="14" >