Strugling with Filters

Thats my Data Struktur And my Report

BelegeEk = there are my supplier invoices
Belege = there are my invoices i sell to my customer

BelgpostionenEk there are all Invoice positions from buying
Belgpostionen there are all Invoice positions from selling

In 1 i want al my Suppliers and the amount i spend to them 

in 2 i want to see wich articel i buyed from them and the amout i spent based on the articels

In 3 i want to se based on the artikel selection of 2 how much money i made with the articels from that supplier

1 and 2 work but i have problems with 3 when i put my measure there and i select a supplier the tabel is empty:

mesure =