First issue:
When posting the formula, please make sure that you use Code Tags (using </> code button) as explained here: How to use this site.
Code tags are required so formulas can be properly displayed and copied without errors.
Second issue:
You are not reading the docs:
https://www.amibroker.com/f?addtextcolumn
that explains the results you are getting
Also here:
Third issue
You are not searching the forum before posting. Always make a search.
If you looked at existing posts you will get this:
https://forum.amibroker.com/search?q=AddTextColumn
The answer to your question is posted on this forum dozens of times.