GetHTML works in a JS Alert, gives error if I assign value

Folks,

Hello from Vermont. Newbie question here. GetHTML works fine for an alert; e.g.

    var field = FCKeditorAPI.GetInstance('QuestionTxt'); 
    alert(field.GetHTML(true)); 

However, if I attempt to assign the output of getHTML to a JS variable, I get the error, Object doesn’t support this property or method:

    var field = FCKeditorAPI.GetInstance('QuestionTxt');
    var value;
    value = null;
    value = field.getHTML(true);
    alert(value);

Thoughts?

Thanks!
Rob
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