left-hand side of assignment operator is not an lvalue

[Designer23]

hello,
I faced an error saying: Error: left-hand side of assignment operator is not an lvalue with QML

property var play: 0
    Button{
        id:play
        x: 212
        y: 385
        width: 39
        height: 40
        Image{
            id:img
            anchors.topMargin: 6
            anchors.fill: parent
            source: "qrc:/images/play.png"
        }
        onClicked: {
            play++
            if(play===1){
                img.source="qrc:/images/pause.png"
            }
        }
    }

How can I solve it.
thanks

[ODБOï]

hi
You use "play" as property name and button id