external SRAM other than IDT 's SRAM

I want to use an external SRAM as my NIOS2's memory, the SRAM is not the IDT's SRAM (IDT71V416) used in the development kit's board. the data ports of the my SRAM are bidirection (inout) ports, but when I create a new component in SOPC builder, the data ports are only input ports, and can not force them to be inout ports. so SOPC builder give this error message:

avalon_tristate_slave_0:slave has write signals but no data signal

avalon_tristate_slave_0:slave has read signal but no data signal

avalon_tristate_slave_0:slave must have a read or write interface, or supprt interrupts