Ionic BLE plugin unable to scan BLE device

I have a BLE device And an ionic app. When i am scanning it using ionic BLE plugin from my app. It was not listed in scanned device list.Whereas i have one another BLE device that is appearing in scanned device list. What is the issue with the first device. Code that i have written to scan BLE devices is.

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