error VGA core

i am currently designing a JPEG decoder using DE2 board. i use Quartus 9.0 sp1 web edition.I use these following IP core and somes are from university program: Nios II processors, on-chip memory, JTAG uart, SPI (3 wire serial), audio and vidoe config (from university program), DE boards ext interface (from university program), PIO , Character LCD 16x2 (from university program), SDRam controller, VGA. i got the message error about the VGA core, and i don't know what i have to do with that. and i need information too about using the SDRam.

here is the message error:

Error: up_avalon_vga_0.avalon_pixel_sink: "up_avalon_vga_0.avalon_pixel_sink" must be connected to an Avalon-ST source

i dont know what to do... i'm a beginner :p

thanks before