Shipping cost and French VAT

Hi gurus,

I have this problem to resolve :

My customer wants to distribute the cost of shipping in an invoice in all items among the weight.

So I have a Shipping condition and it's OK. No is coming the VAT problem !!!

The shipping cost is at VAT 19,8% and if I have an Item at VAT 5,5% the distribution ok the shipping cost is also based on 5,5 % and not on 19,8%

So how can I distribute the shipping cost and have the real good one VAT ?

Thanks

Stephane