DE2-70 ssram IS61LPS51236A not working with qsys and nios2

Hi,

I'm trying to use the ssram on the DE2-70 board without any luck for a nios2 system build with qsys. When loading the program on the FPGA, I get the error that the elf file could not be loaded.

I instantiated a Generic Tri-State Controller with the Settings from "ISSI IS61LPS25636A-200TQL1" which is pin compatible to the IS61LPS51236A on the DE2-70 board (see attached figure). And connected the pins to the best of my knowledge as following:

 
--tri-state controller to ssram connections:
            ssram_out_tcm_chipselect_n_out    => oSRAM_CE1_N,   
            ssram_out_tcm_byteenable_n_out    => oSRAM_BE_N,   
            ssram_out_tcm_outputenable_n_out  => oSRAM_OE_N, 
            ssram_out_tcm_write_n_out         => oSRAM_GW_N, -- uncertain
            ssram_out_tcm_data_out            => SRAM_DQ,          
            ssram_out_tcm_address_out         => oSRAM_A,        
            ssram_out_tcm_begintransfer_n_out => oSRAM_WE_N  -- uncertain
        );
-- unconnected:
        oSRAM_ADSC_N <= "1";
        oSRAM_ADSP_N <= "1";
        oSRAM_ADV_N <= "1";
        oSRAM_CLK <= iCLK_50; 

Does any one have any suggestions what to try?

Regards, Tobi