Buy stop after hours question

Newbie question. I was setting up an after-hours buy stop last night on the GBP/USD and didn't realize I could not set up a buy stop at a price below the daily close price.

1) What is the reasoning behind the rule?
2) Is that normal for brokers?

Thanks much,

Kent F.

I like the new forum layout. At the bottom of this post are "related threads" here's the link. That will answer your question.
Buy Stop & Sell Stop basic question

thanks - makes sense to me now - good reading, thanks for the link.

Kent F.