Signed security timestamp first

Hi,

I would like to create a SOAP request with a signed timestamp.
I managed to add the signature, I managed to add the timestamp.

But, the timestamp is the last element in the security header whereas it should be the first.
If I change signature <-> timestamp order in the outgoing request, I get an error where the signature complains it does not find the timestamp element.

Does somebody has a solution ?

Thanks,