Analisis Pembentukan Perilaku Pembelian Channel melalui Program Promosi Penjualan: (Studi Kasus Program Promosi Penjualan PT Bintang Baru Indonesia Perkasa Raya terhadap Agen) = Analysis of The Formation of Channel Buying Behavior Trough Sales Promotion Program: (Case Study Sales Promotion Of Pt. Bintang Baru Indonesia Perkasa Raya)