DE0-Nano, Download .elf fail when using EPCS64

Hi, everyone~ I use DE0-Nano board, and I want to burn my .sof and .elf into flash memory, and make it self-booting. I use SDRAM as my memory in my SOC, and I have added EPCS Controller into it. Also I set EPCS for reset vector in CPU and all the dual-propuse pins as regular I/O. But when I run my program in NIOS II, there's a error:Verifying 00000000 ( 0%)
Verify failed between address 0x0 and 0x1F
Leaving target processor paused I don't know why it happens. Please tell me how to solve it. Thank you!