How to activate a shape by name and change text, font ... ?

I recorded some macros to automate my workflow to laser some wood with names. Now i try to control Corel Draw X7 by c#. Amazing ...
I found some code in the internet and a lot of very efficient code snippets from shelby, by not one snippet with my (beginnsers) problem.

There is a draw with two shapes, one with some lines, one (named "Ebene 1") with the text to change.
The code
doc.ActivePage.TextReplace ("John Doe", "blubb", false, true);
is working, if the shape "John Doe" is selected. But not, if the draw is opened without a selection.
My wish is to change every text on shape "Ebene 1" to the text "blubb" and set a textfont and size and, for luxury, to get a response via com about the result.

Is someone there to take my hand?
regards and a big "thank you" for all the support you give also at the other forums!
Ralf