I found the issue. Tried to delete this post but I am not even authorized to delete my own post.
So I would share what I did wrong for others to learn from this.
Some Index pairs such as WS30 (Dow Jones) or NDX (Nasdaq 100) uses different decimal calculations. The 100 pips SL I had set in the block was actual not even a pip. That setting simply was too small to open the trade.
Thank you for your time reading this.