Item cannot be found in the collection corresponding to the requested name or ordinal

So the example is not working?

I suggest you try something very simple to output a value, e.g.

function search_with_loop() {
    DDT.ExcelDriver("C:\\Temp\\Book2.xlsx", "Sheet1");
    DDT.CurrentDriver.DriveMethod("SearchPerson.search_for_existing_record");
}

function search_for_existing_record() {
    Log.Message(DDT.CurrentDriver.Value("Person ID"));
}

The message "...requested name or ordinal" usually indicates that the column name is not correct or not formatted correctly. You have the following, the latter, does not have an underscore.

DDT.CurrentDriver.Value("Last_Name")
DDT.CurrentDriver.Value("Person ID")

Okay, now put line 10 back and try it again. Uncomment each of the lines one at a time, going up, until the error occurs again. That tells us the source of the problem.

I'm not sure what your code is doing, but it's best to try the example shown in https://support.smartbear.com/testcomplete/docs/reference/program-objects/ddt/exceldriver.html and ensure you meet the requirements shown in https://support.smartbear.com/testcomplete/docs/testing-with/data-driven/drivers.html

I fulfill all the requirements but it's not working. I'm lost at some point

So you mean my column header might be the problem?

I removed the underscores or spaces.
Instead of Person ID -> PersonID 
Last_Name -> LastName  

your code snippet that you send me worked but my code is still failing with same error. 

I start to think that it is possible to be about the input box that I try to pass the values of Excel files. 

What do you think?

function searchForExistingRecord()
{
  navigate_person_search_form();
    
  let page = browser.pagePersonEidss;
  page.Wait();
  let textbox = page.formPersonsearchform;
  let textbox3 = textbox.textboxPersonId;
  
  textbox3.WaitProperty("Enabled", true, 2000);
  
  let str = DDT.CurrentDriver.Value("PersonID");
  Log.Message(str);
  
  textbox3.setText(str);
  
  textbox.buttonSearchbutton.ClickButton();
 
  aqObject.CheckProperty(textbox.hyperLinkInGrid, "contentText" , cmpEqual, DDT.CurrentDriver.Value("PersonID"));
   
  browser.Close();
}

I really hate this new forum - I had earlier saw a screenshot of your spreadsheet (I think it was yours!), which I can't seem to find now!

From what I remember from the screenshot, columns C, D and E on row 3 had a few empty values. This might cause issues with DDT.ExcelDriver, or you might need to deal with empty value or error that's returned by DDT.CurrentDriver.Value() method.

I suggest you try the example that I have provided, but include all column to output the values, e.g.

var a = DDT.CurrentDriver.Value("Column A");
Log.Message(a);
var b = DDT.CurrentDriver.Value("Column B");
Log.Message(b);
var c = DDT.CurrentDriver.Value("Column C");
Log.Message(c);
DDT.CurrentDriver.Value("and so on");
...

This will given an indication as to what row and column is causing the issue.

With DDT, you need to ensure that the headers are correctly formatted, and the data is correctly formatted too. 

Here's an example where column F does not exist, error message is shown.

The example that I have provided, which you have tried, and works on your end. Indicates that there is nothing wrong with using DDT.ExcelDriver. I suggest you debug your code to see exactly what it's doing, step through each line of code, and hopefully this will pin point the error.