Can't config the cyclone ii EP2C20Q240

[Altera_Forum]

Hi guys, 

 I'm a student learning FPGA,I bought a cyclone ii EP2C20Q240 and want to download a program .But it doesn't work. THE 50MHZ crastal to the chip is ok, and the chip's vcc and gnd is also ok; Following the config handbook ,i connect the chip as it reads JTAG Configuration of a single device using a download cable . BUT i can't download any program by the quartus ii software. Anyother connections does the chip need? I just want to realize the basic function.  My English is just so-so, but can you help me ?

[Altera_Forum]

If there is no need to give external power supply then you made enough connections.No need to have more connections. 

check that driver for that download cable installed succesfully and make sure that in hardware configuartion u selected your proper hardware like "use-blaster" or anything that you are using.

[Altera_Forum]

:) Thank you for your help very much. But it also doesn't work .As my connections are right, when i download the program by quartus II with the usb-blaster, in the option programmer ,it can also find the hardware USB-0 , but when i click start, it prompts "error:can't access JTAG chain". 

What do i need to do next?   Hoping for your help online;

[Altera_Forum]

Thanks that you told me error message.I think i got. 

You choose wrong device to download your program. check it ,i think it will solve your problem. Select proper FPGA.

[Altera_Forum]

I think the device is ok ; the name is ep2c20q240. We find a new problem: the source may be not steady; and the 50mhz crystal's output is 2.2v-1.0v. Can the 50mhz crystal make the fpga device work normally?

[Altera_Forum]

I dont feel it is crystam problem,if everything seems to be ok then replace your download cable.  

Are you using only quartus,right? no other supported softwares? so i think it should not have any problem.

[Altera_Forum]

Yes,and there is juat the quartus II 8.0 I can use.I will try another usb-blaster to check again;  

Thank you very much , i know the problem may be not easy but i will try my best to do it.  I will always search the altera forum later and improve myself.  Best wishes for you! Friend.