To my understanding you are trying to import data from Matlab workspace to Simulink using “to workspace” block.
Instead of using “To workspace” block you should use “From workspace” block to use data from Matlab Workspace. Kindly refer to the documentation of “From workspace” block which is attached below for better understanding-
You can refer to the documentation attached below to look for the different ways in which you can load signal for simulation-
Hope this helps!