LQE datasource to RAM always failed on indexing

Hi

I have  created required Oauth Consumer Key/Oauth Consumer Secret in RAM side via Cross-Server Communication.
Then I added a datasource in LQE to access RAM TRS but failed in indexing with error Unauthorized(401)

I'm sure I used correct Consumer Key and Consumer Secret when creating this datasource.
Any other reason could cause this problem?

BTW, which user I need to add as Functional User ID when creating Consumer info in RAM side? use "Repository Process" or "lqe_user"

Besides, I tried to change the Consumer Secret but I found LQE won't take the update and always using the previous Secret key. (The string length of the secret key won't be the same as the one I entered in RAM side)
Anyway to completely remove the datasource settings from server side?

Thanks and Regards