How to use SSugestionTextBox?

Hi, I am trying to use SSuggestionBox to display some possible questions from an array. I have the following code but I get the error ‘cannot access protected member declared in class’. If I set the variable to public I get another error.
In the header file there is this code:

class PROJECT_API SMyChatWidget : public SCompoundWidget
{ ...
    void Construct(const FArguments& InArgs);
    TSharedPtr< SSuggestionTextBox > InputTextBox;
...
}

In the cpp file there is this code:

void SMyChatWidget::Construct(const FArguments& InArgs){
...
SAssignNew(InputTextBox, SSuggestionTextBox)
...
TArray<FString> suggestions = { TEXT(hey), TEXT(Hey)};
InputTextBox -> SetSuggestions (suggestions, true);
}

Any help is appreciated. Thankyou!