EOS 5DS R mirror lockup via Canon remote RC-6

[ACCC]

Canon 5DSR
I can't get the mirror to lock up during exposure.
I have set both live view and silent mode 1 to eliminate vibration, this should lock up the mirror during exposure.
I suspect the RC 6 that I am using so as not to touch the camera is the problem, one must set the self timer in the camera in order for it to work, this seems to disable the mirror lock up. I suspect a cable release is necesary in order to be able to keep the mirror locked, Is this the problem? Or is it possibly something else I am doing wrong? Thanks in advance.

[p4pictures]

Yes you need to use a cable release with mirror lockup, the R6-6 won't work. 

[Waddizzle]

I use the shutter delay timer and mirror lock up all the time. However, I don’t often use Live View, but it works, too.  

I don’t readjust the shutter, either. I would think setting silent mode and mirror lock up would cause issues.