Orders rejections due to one of the above reason, but also because of the allowed distance from current price to put pending orders (known as “minimal distance”)
Different trading hours (ProOrder code launched in a different time zone / custom hours, by the user)
Coding problem: division by zero error, null or negative periods for indicators, ..
Lack of responsiveness of IG demo servers (if IG is the broker), although this has improved considerably since last year.
