You will never know, or at least not while you continue to swallow the exceptions that might give you in info you need:
While MasterReader.Read()
StrArr(0) = (MasterReader("CPF_No".ToString))
StrArr(1) = (MasterReader("Name".ToString))
StrArr(2) = (MasterReader("Designation".ToString))
Try
LvMasterCmd.CommandText = "INSERT INTO LeaveMaster" &
"(CPF_No, Name, Designation, MNT, YR, LeaveStatus)" &
"VALUES ( @CPF_No, @Name, @Designation, @MNT, @YR, @LeaveStatus) ;"
LvMasterCmd.Parameters.AddWithValue("@CPF_No", StrArr(0))
LvMasterCmd.Parameters.AddWithValue("@Name", StrArr(1))
LvMasterCmd.Parameters.AddWithValue("@Designation", StrArr(2))
LvMasterCmd.Parameters.AddWithValue("@MNT", CmbMonth.Text)
LvMasterCmd.Parameters.AddWithValue("@YR", CmbYear.Text)
LvMasterCmd.Parameters.AddWithValue("@LeaveStatus", "N")
LvMasterCmd.ExecuteNonQuery()
Catch ex As Exception
End Try
End While
Never do that: you discard the error, and any information it might include that could help you to actually solve the problem - you even hide the fact that an error occurred at all, so it just looks to you that not all the updates happened...