so the error being returned is:
:Line item 1 is invalid.:
line item 1 in the request is:
x_line_item=182<|>Buck N Cute Changing Pad<|>
Buck N Cute Changing Pad NCP1
<|>1<|>12<|>YES&
it looks like the problem is in the description being passed.
Check the description for this item for special characters or html coding.