Can someone quickly help me. I am making the recipe as usual and never had a problem til now. For some reason the icing isn't thickening up as usual it is staying runny. Do I keep beating? Do I add more sugar? Will this ruin my cookies if I thicken? Or do I throw out and start again??
TIA

I would first try adding more sugar and see what happens...maybe 1/2 c. at a time.

you have to make sure you beat for 10 min. Also if it is humid, this will affect it.

Thankyou for your replies.
I am in Australia and yes it has been a humid day today.
I did beat for the 10 min like I usually do and it was just really runny.
So I beat it for another 10 minutes and it thickened up. Not as thick as usual but usually it goes really stiff, so I was happy with this consitency.
I really did panick as I have made it several times before and never had this problem. So I am putting it down to the humidity.
Thankyou again for your help.

I've never had that problem with Antonia's icing, but I have had it frequently with regular royal. I always put it down to having a wayward speck of grease on the beater or bowl. And if it's that....you have to start over, unfortunately.

Perhaps some grease in the bowl or on the beaters? Just a little will do RI in. I wipe my bowl and paddle down with white vinegar before using.