unable to get the clicked button value

I am creating a new field for each word in my pdf and giving action for each button using Acrobat Pro, My problem is I am unable to get the value of the button that has been clicked. Here is my code

var numWords = this.getPageNumWords(0);

for ( var j = 0; j < numWords ; j++) {

          var nThWord;

          var cScript;

          nThWord= this.getPageNthWord(0, j);

          var wrdRect = this.getPageNthWordQuads(0, j);

          if (nThWord != '') {

                    cScript = "app.alert(nThWord);";

                    console.println(nThWord);

                    var fldRect = [];

                    fldRect[0] = wrdRect[0][4];

                    fldRect[1] = wrdRect[0][5];

                    fldRect[2] = wrdRect[0][4] + 3;

                    fldRect[3] = wrdRect[0][5] + 3;

                    var oFld = this.addField(nThWord, "button", 0, fldRect);

                    if (oFld != null) {

                              oFld.buttonSetCaption("");

                              oFld.borderStyle = border.s;

                              oFld.fillColor = color.gray;

                              oFld.textColor = color.white;

                              oFld.lineWidth = 1;

                              oFld.setAction("MouseUp", cScript);

                    }

          }

}

PS: The JS API says setAction() function does not work in Adobe reader but I tested in Adobe reader 11. I was able to execute setAction() function.