Trouble using SKSE Input.Holdkey() with mouse buttons

[Brehanin]

I have successfully used the Input.Tapkey() command to create customizable hotkeys for the shouts in my mod, Better Vampires, but I cannot for the life of me get the script to tap or hold a mouse button down ...

 

Here is a sample of my script. This snippet is intended to cast Mortal's Mask by equipping it in the left hand, then simulating a RMouse button press to cast it.

        If BVKeyPressed == BVMortalsMaskHotkey
            If Game.GetPlayer().HasSpell(VampireRemoveHateSpell)
                Game.GetPlayer().EquipSpell(VampireRemoveHateSpell,0)
                Int MappedLeftKey = Input.GetMappedKey("Left Attack/Block")
                Input.HoldKey(MappedLeftKey)
                Utility.Wait(3.0)
                Input.ReleaseKey(MappedLeftKey)
            EndIf
        EndIf

Will Input.Tapkey() and Input.Holdkey() not work for simulating mouse buttons? They work perfectly fine for keyboard keys.

I am using all the correct DXScancodes too - I've confirmed that the MappedKey is 257 (the RMouse button).

 

Any help woudl be greatly appreciated! Can I do this differently?

 

P.S. Ive already tried using the Cast spell procedure, but it casts automatically and doesn't use any Magicka. Also, with the cast procedure, once-a-day powers can be spammed indefinitely, so I wanted to make the use and casting as normal as possible.