Ionic2 BLE plugin unable to scan bluetooth sensor

I have a sensor that have the bluetooth. When i am scanning it through BLE plugin scan method. That method is unable to scan it. And when i am scanning it from chromeScanner that is able to scan it. Below is the code that i am using for scan. A different sensor that also have the bluetooth.
I am able to scan that. But the first one is not coming in scan list.
What is the issue ?

        this.bleService.scan([], 10).subscribe(
            device => this.onDeviceDiscovered(device),
            error => this.scanError(error));
        setTimeout(() => {
            if (this.deviceList.length > 0) {
            } else {
                this.toastService.presentToast("No device found");
        }, 10000);