Did you pull the HOLD pin high?
BTW, you might be interested to know there is now an SPI SRAM chip with
larger store size, which runs at 5V or 3.3V, and comes in DIP8 besides SOIC8.
I'm using this chip, and it's much more convenient than SOIC8 and 3.3V.
Although this may not be a factor, the other thing is, if you use a pin other
than Arduino D10 for CS, you still have to set D10 = output, else the SPI
peripheral will revert to slave mode.