Unable to format existing Portion

Hi

i have a Paragraph, where all is formatted bold.
I need to chanage one existing Portion to non-bold.
I tried:
autoShape.TextFrame.Paragraphs[1].Portions[0].PortionFormat.FontBold =NullableBool.False;

No effect!!!

How to do it?

Thanks

uli

@uboddenberg,

I have observed the issue shared by you and like to share that in your sample code you are accessing the second paragraph of your text frame and removing the boldness for first portion of text. There seems no issue in code. Can you please share the source presentation, used sample code and desired output presentation fore reference.