[weiden] 19623: minor fix in SetupDiGetDeviceInstanceIdA

minor fix in SetupDiGetDeviceInstanceIdA
Modified: trunk/reactos/lib/setupapi/devinst.c
  _____  

Modified: trunk/reactos/lib/setupapi/devinst.c
--- trunk/reactos/lib/setupapi/devinst.c	2005-11-26 10:18:02 UTC
(rev 19622)
+++ trunk/reactos/lib/setupapi/devinst.c	2005-11-26 10:18:24 UTC
(rev 19623)
@@ -3493,7 +3493,7 @@

                                           DeviceInstanceIdW,
DeviceInstanceIdSize,
                                           RequiredSize);
 
-        if (DeviceInstanceIdW != NULL)
+        if (ret && DeviceInstanceIdW != NULL)
         {
             if (WideCharToMultiByte(CP_ACP, 0, DeviceInstanceIdW, -1,
                 DeviceInstanceId, DeviceInstanceIdSize, NULL, NULL) ==
0)