Consignment accounting and revenue recognition

when the principal collects the amount of sale made then the entry would be

creditors

     to cash / bank

and but why the principal is paying VAT to agent, bcz agent cannot show the sale made on behalf of principal  as sales in his book

Dear sir,

i have one client , who in doing business in C & F, then how recognised revenue in the books of clients.

sales, purcheses & stock have to shown in P & L A/c or not./directaly commission  shown in P&L A/c.