Reverb channel as AUX or Stereo Bus?

Hi,
 
When I want to use SENDS to send multiple channels to a REVERB channel, do SEND to an AUX channel or STEREO BUS?
 
I had an AUX channel but now out of the blue, NONE of the sends want to work...

I'm new to Aux tracks but I already have a definite policy on the use of AUX v BUS, as follows:

• If I will be needing to adjust settings later during the mixing stage, then I use a BUS.
• If I intend leave it alone once it is set up, then I use an AUX.

But I have not really explored the possibilities of Aux tracks yet, so this may change.

Interesting...
Coming from live consoles and being a long-time user of another DAW, Auxes and Busses are conceived of differently. 
Typically, you would use an AUX for Effects, as then you can send many channels to a particular effect (i.e. Room or Hall or Plate reverb) or an Effect Chain (i.e. delay, verb, compression, shelving EQ, etc.) and determine the AMOUNT you desire to send per channel. For example, it would be standard to have the reverb set at 100% on the Aux channel, and then send differing amounts to taste from each source channel (i.e. maybe -20dB on a Lead Vocal, and -15dB on backup vocals - to highlight the lead vocal). 
 
Meanwhile, think of Busses for Grouping Channel Outputs and for mixing. So, any groups of channels that you want to send through the same EQ or Dynamics chain - and control for volume as a group (i.e. Drums, Guitars, keyboards, orchestra, backing vocals, etc.) - you assign their outputs to Subgroups. 
 
Then software that emulates hardware VCAs becomes another sweet option, for controlling groups of faders (but no audio passes through). It's worth thinking of WHY such a category exists and what advantages it has compared to another category.