gate-level simulation using skywater and modelsim

[zliu1Charlotte]

Dear all,
I loaded my post-syn netlist, .sdf, testbench, and skywater cells using modelsim command line.
but it seems like my gate-level simulation's inputs and outputs are all remained as x. and it shows no errors.
It seems like none of the skywater cells are actived and such?
I looked into each cells, and I see that for example a inv, and its input and output are both x.
I feel like I am not loading them correctly in vsim?
btw rtl-level simulation using vsim worked as expected.
vsim complains about the wire type so I changed all the needed cells to wire instead of none.
But I do not know why all inputs and outputs remained x.
Let me know if you have seem this before. if you need any files i can provide them thanks.