The "display size" order attribute may not be specified for this order message?

I have been trading with IB for nearly twenty years and use the classic TWS, and when I was trying to put a futures stop order in late this afternoon (before 4:14 EST), I could not place the order. Instead, I received the following message: the "display size" order attribute may not be specified for this order.

I could not find the message in the long index of message codes.

I have tried to configure the order attributes section.

Nothing seems to work.

I am not trying to put in a complicated order: merely a buy stop order slightly above the market No conditions. I don't even have the "display size" on my quote screen.

What should I do? Thank you.

 

Are you long or short the position?

Or are you trying to create a position with a stop buy?

 

Already long and wanted to add more.

 

I have never seen that message before...ever.

 

It does it only for futures, not for stocks.

 

Looks like a temporary issue. I’d try again after a while, even restarting TWS just in case.

 

I think I may have figured it out.