PayPal API: the sum of the basket does not match the amount of orders

There are many reports about this error, but all of them do not apply to me. I really don't understand why the amounts do not match. I have an ITEMAMT that matches AMT0 * QTY0. And AMT corresponds to ITEMAMT + SHIPPINGAMT. I checked the documents again and again, and it really should work like that. It works when I completely remove the delivery from it ...

The AMT in the validation URL is also 73.9.

I really hope someone is familiar with this very confusing error and knows what I'm doing wrong ...

Thanks in advance

Array
(
    [TIMESTAMP] => 2013-01-24T22:56:09Z
    [CORRELATIONID] =>
    [ACK] => Failure
    [VERSION] => 62.0
    [BUILD] => 4181146
    [L_ERRORCODE0] => 10413
    [L_SHORTMESSAGE0] => Transaction refused because of an invalid argument. See additional error messages for details.
    [L_LONGMESSAGE0] => The totals of the cart item amounts do not match order amounts.
    [L_SEVERITYCODE0] => Error
)
Array
(
    [PAYMENTREQUEST_0_PAYMENTACTION] => Sale
    [L_PAYMENTREQUEST_0_NAME0] => XXXX
    [L_PAYMENTREQUEST_0_NUMBER0] => 30533
    [L_PAYMENTREQUEST_0_DESC0] => XXXX
    [L_PAYMENTREQUEST_0_AMT0] => 30.95
    [L_PAYMENTREQUEST_0_QTY0] => 2
    [PAYMENTREQUEST_0_ITEMAMT] => 61.9
    [PAYMENTREQUEST_0_TAXAMT] => 0
    [PAYMENTREQUEST_0_SHIPPINGAMT] => 12
    [PAYMENTREQUEST_0_INSURANCEAMT] => 0
    [PAYMENTREQUEST_0_AMT] => 73.9
    [PAYMENTREQUEST_0_CURRENCYCODE] => USD
    [REQCONFIRMSHIPPING] => 1
    [PAYMENTREQUEST_0_SHIPTOSTREET] => XXXX
    [PAYMENTREQUEST_0_SHIPTOCITY] => XXXX
    [PAYMENTREQUEST_0_SHIPTOSTATE] => XX
    [PAYMENTREQUEST_0_SHIPTOCOUNTRYCODE] => XX
    [PAYMENTREQUEST_0_SHIPTOZIP] => XXXXXX
    [PAYMENTREQUEST_0_SHIPTOPHONENUM] => XXXXXXXX
)