diff --git a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/sal/LocalDeviceServiceImpl.java b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/sal/LocalDeviceServiceImpl.java
index 6652d22f..2c7fdc1a 100644
--- a/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/sal/LocalDeviceServiceImpl.java
+++ b/sec-beidou-rtcm/src/main/java/com/imdroid/sideslope/sal/LocalDeviceServiceImpl.java
@@ -84,7 +84,7 @@ public class LocalDeviceServiceImpl implements DeviceService {
                 }
             }
 
-            if(device.getParentId1() != null || !device.getParentId1().trim().isEmpty()){
+            if(device.getParentId1() != null && !device.getParentId1().trim().isEmpty()){
                     subDeviceCache.invalidate("back_"+device.getParentId1());
             }
             deviceCache.invalidate(deviceId);