Int8 calibration Algorithm select : has no choice to select

for the same layer , choose algorithm for int8 calibration process has much less choice to inference process.

When I want to choose algorithm in int8 mode for ssd model. It seems conv1/dw + relu1/dw layer has algorithm caskconvolution Tactic=1825138533642645384 can be used ,but why the number of choice is 0.