diff --git a/HikNvr.go b/HikNvr.go
index 2d036c7..7e7e458 100644
--- a/HikNvr.go
+++ b/HikNvr.go
@@ -84,7 +84,7 @@ func (h *HIKNvr) UTCDiff() int {
     if h.State {
         data := nvrUTCDiff(h.core)
         h.mux.RUnlock()
-        if nvrUTCDiff(h.core) == 500 {
+        if nvrUTCDiff(h.core) == 5000 {
             h.mux.Lock()
             h.State = false
             h.mux.Unlock()
@@ -97,5 +97,5 @@ func (h *HIKNvr) UTCDiff() int {
     } else {
         h.mux.RUnlock()
     }
-    return 1000
+    return 5000
 }
diff --git a/library.cpp b/library.cpp
index 254bd39..4be7c2b 100644
--- a/library.cpp
+++ b/library.cpp
@@ -60,6 +60,8 @@ char *CheckTimeRegionWithMonth(void *PtrHIKNvr, int year, int month) {
 
     if (nRet == 0) {
         res = HIKNvrObj->TimeToJson(select_time, &available_date_vec).dump();
+    }else{
+        res = "";
     }
     char *cString = new char[res.size() + 1];
     std::strcpy(cString, res.c_str());
@@ -77,6 +79,8 @@ char *CheckTimeRegionWithDay(void *PtrHIKNvr, int year, int month, int day) {
     int nRet = HIKNvrObj->CheckTimeRegionWithDay(select_time, available_time_vec);
     if (nRet == 0) {
         res = HIKNvrObj->TimeToJsonInDay(select_time, &available_time_vec).dump();
+    }else{
+        res = "";
     }
     char *cString = new char[res.size() + 1];
     std::strcpy(cString, res.c_str());
diff --git a/src/HIKNvr.cpp b/src/HIKNvr.cpp
index bd1fdbf..6154314 100644
--- a/src/HIKNvr.cpp
+++ b/src/HIKNvr.cpp
@@ -30,7 +30,9 @@ bool HIKNvr::InitNvr(std::string ip, std::string port, std::string username, std
 int HIKNvr::GetNvrUTCDiff(){
     NET_DVR_NETAPPCFG struNAC = {0};
     DWORD ZoneSize = 0;
-    NET_DVR_GetDVRConfig(LoginID, NET_DVR_GET_NETAPPCFG, 0, &struNAC, sizeof(NET_DVR_NETAPPCFG), &ZoneSize);
+    if (NET_DVR_GetDVRConfig(LoginID, NET_DVR_GET_NETAPPCFG, 0, &struNAC, sizeof(NET_DVR_NETAPPCFG), &ZoneSize)){
+        return 5000;
+    };
     int nDiffHour = struNAC.struNtpClientParam.cTimeDifferenceH;
     int nDiffMin = struNAC.struNtpClientParam.cTimeDifferenceM;
     nDiffTotalMin = (nDiffHour < 0 ? -1 : 1) * (abs(nDiffHour) * 60 + nDiffMin);