alt_flash_open_dev return 0

Hi all

I want to read and write the 4M flash on DE2. I add a tri-state bridge and connect the CFI to it in the sopc builder. But when I use alt_flash_open_dev to open the flash, it always return 0. Could anyone give me some advise? I use quartusII 9.1 and niosII 9.1.

thx!

I made a mistake. I check the flash again. It is 1M and the type is 29LV800TE-90PFTN, the datasheet said it compatible with JEDEC standard. But the sopc is CFI standard. Can this be the problem?

ps: When I use the nios flash programmer, it shows no CFI table found. But the data shown below is correct. I set them by the control panel of DE2.