ARKit application shows line between lips color. How can we get rid of that ?

Hello Everyone,

As I have mentioned my app shows a line between two lips for the application of virtual lipstick color change. Following is my code used for lip color

    let faceGeometry = ARSCNFaceGeometry(device: device)

        let faceNode = SCNNode(geometry: faceGeometry)         faceNode.geometry?.firstMaterial?.transparency = 0         guard let faceAnchor = anchor as? ARFaceAnchor else { return nil }         faceAnchors.insert(faceAnchor)

        let material = faceGeometry?.firstMaterial!

//        Shape of lips         material?.diffuse.contents =  imageLiteral(resourceName: "lipShape_old")

        // Lipstick color         material?.normal.contents = lipstickColor         material?.multiply.contents = lipstickColor

        // More realistic         material?.lightingModel = .physicallyBased         material?.transparency = 0.82

     masks.insert(faceNode)

        return faceNode

Please check that. Any help will be appreciated. Thanks