Delay Between x2 RA2 Select In-line Dimmer when switched from the same Pico

[MegaWot]

I have x2 RA2 Select In-line Dimmer that Operate two sets of downlights both have 18 downlight on each to spread the load
Both RA2 Select In-line Dimmer are paired to the same Pico switch

When switching sometimes there is a large delay between when both sets of lights come on sometimes only one set will come on and sometimes it works fine

Its not the downlights its definitely the In-line Dimmer as I'm get 0v out of one and 240v out the other
Its or so not just one of the In-line Dimmer that is lagging sometimes it will be 1 sometimes it will be the other
I or so have the same thing happening on a different set of lights with the same set up with x2 RA2 Select In-line Dimmer and x1 Pico switch
So I don't think there are faulty and that would mean all 4 are faulty

Is there a better way to pair them then holding the buttons ?
or could it be range as it seems to work fine when I'm right next to them

If it is range is there a way to extend range with out Wi-Fi as Wi-Fi is not available in this install

[randyc]

You said they work when you are close to the devices so I don't think it is a pairing issue. The next step is adding a main repeater and possibly a wireless repeater.