Buying stock does not transfer from Bank Account

[Stephan Pouh]

I am using GC 1.8.1. I also track (buy, sell, update price) with GnuCash. 
However, when I buy a stock (which is a split transaction) the numbers show 
on the the split screen, but the sum of the expenses does not transfer 
(deduct from my balance) of the  account the purchase is charged to.

I have tried to find anything on the internet regarding my possible incorrect 
use or a bug report, but was unable to find a hint as to what is wrong.

Regards,

Stephan