Javafx wrong error marked

in FXML this

<ComboBox fx:id="cmbaction" layoutX="876.0" layoutY="469.0" prefHeight="23.0" prefWidth="187.0">

                  <items>

                    <FXCollections fx:factory="observableArrayList">

                      <String fx:value="1" />

                      <String fx:value="2" />

                  </items>

                  <stylesheets>

                    <URL value="@../framework/resourcesimg/Style.css" />

                  </stylesheets>

                </ComboBox>

is marking FXCOllections in red as an error and is not.