Matrix info not saved

[artmem]

I have a form with a custom matrix field. It displays properly on the front end (though I can't get the "add a block" button working), but the data entered isn't saved when I submit the form.

My Matrix handle is 'parts' and the only block is 'part'. I'm using code based on the example in the docs:
<input type="hidden" name="fields[parts][new1][type]" value="part"> <label for="frm_partNumber">Part Number</label> <input type="text" id="frm_partNumber" name="fields[parts][new1][fields][partNumber]"> <label for="frm_description">Description</label> <input type="text" id="frm_description" name="fields[parts][new1][fields][description]"> <label for="frm_quantity">Quantity</label> <input type="text" id="frm_quantity" name="fields[parts][new1][fields][quantity]">
Am I missing something for getting the data to save?