Error:Service ... for device ? not found

Hello , i m new to the library .i have finally successfully found my device using the library . what i want to do now is writing characteristic in order to control my device . the service UUID and characteristic UUID are given . so i m trying to do it using this code (looks bad but i will improve it when it will work :p )

startScan() {
        this.setState({scanning: true});
        this.manager.startDeviceScan(null, null, (err, device) => {
            if (err) {
                alert(err);
                return;
            }
            if (device.name === 'Wearable 4') {
                alert('found it');//this is shown
                this.manager.stopDeviceScan();
                this.setState({scanning: false});
                device.connect()
                    .then((device) => {
                        alert(device.name + ':' + device.id);//this is shown
                        device.writeCharacteristicWithoutResponseForService(
                            "713D0000-503E-4C75-BA94-3148F18D941E",
                            "713D0003-503E-4C75-BA94-3148F18D941E",
                            "0xff000000"
                        ).then((success) => {
                            alert(success);
                        }).catch((error) => {
                            alert(error)
                        })
                    })
                    .catch((error) => {
                        alert(error);
                    });
            }
        });

i m always receiving " Error Service 713D0000-503E-4C75-BA94-3148F18D941E for device ? not found.

I appreciate your help and thank you in advance

[dariuszseweryn]

Yes, it is

[akshayoyo16]

Is there a concept of timeout in this startDeviceScan function ?? like if i only want to scan for like 20 seconds, & if i dont find the device i am looking for in 20 seconds then i dont want to move further.