fpga is configured successfully but cannot work

Hi all

My project has two FPGAs and these two FPGAs can be configured separately via their JTAG headers.

Besides, the two FPGAs shares an epcs in the multi-device AS configuration mode.

When I download a sof file to one FPGA via the JTAG header.

Quartus II programmer shows me "success" but the FPGA doesn't work.

The sof file simply turns on/off a led and the pin assignment has been checked.

For example:

assign led = 1'b0; // 1'b1

However, after I add a serial flashloader in my top module and download the new design, the FPGA works.

   sfl_v sfl_v_inst
   (
   	.noe_in(1'b0)
   );

To my understanding, the serial flashloader is added only when the flash is indirectly configured from JTAG through FPGA. Besides, the configuration file should be jic instead of sof.

So what I find in my project is really confused me...

Does anyone have some ideas about my problem?

Thanks.