Using CompareToSet with a simple list of strings

I must be overthinking this or something, because this is ridiculously simple, but I can't get it to work.

I'm writing a regression test to verify that a drop down list contains the correct set of choices.  I have a feature file with a simple 1 column table containing the list:

Then the dropdown list is populated with the following choices:
| DropDownChoice |
| Choice 1 |

| Choice 2|

| etc        |

In my step definition, I'm retrieving the choices for the drop down list from the page object as List<string>,

and then I want to to use table.CompareToSet(list)

public void ThenTheDropdownListIsPopulatedWithTheFollowingChoices(Table table)
{
List<string> choiceList = _pageObject.getDropDownChoices;
table.CompareToSet(choiceList);

}

I mean, for what I want to do, it should be just that simple. But no matter what I do, I keep getting "Field not found: DropDownChoice"

I even tried creating a DropDownRecord type with a single string field named DropDownChoice, and using a Linq statement to create a list of that record type from the list of strings, but I still get the same error.

Can somebody give me some tips as to what I'm doing wrong?

Thanks in advance.

Dave Hanna