Can I use 3D Widget Interaction to simulate the key that was set in the action mapping (Project input setting)??

Hello everyone,
These days i’m doing a VR project.
I want to communicate with the 3d UMG widget.
I define an input action called Grab to update the widget and use the left mouse button to call it, and I use the Press Pointer Key to simulate the left mouse button by Motion Controller Trigger, but when I hold the trigger it can’t call the Grab event.
Am i doing something wrong?
here is the pic.
Looking forward the answers, Thank you guys.!