how do I arrange time for a schedule on vba - excel

Question

I am working on this schedule in Excel that will let me know if am scheduling only one person at a specific shift. So what the macro does it goes over a specific list that I have attached and checks their starting time and ending time. I want the macro to let me know if I schedule someone at a specific time that if there will be overlapping someone else. The following code is working, but now that I am testing to see if it works I put a name, app server they will be running, starting time and ending time. So the macro goes over a loop to check the table that I provide on excel, but I'm getting an error on the time. For example if I put the starting time at 6:00 am and the ending time at 6:30 am and on the table provided I have someone else running that app at rows tart time at 5:59 am to rowendtime= 6:35 am it should show me a "conflict" because they are overlapping but for some reason it is showing "no conflict" Any help would be really appreciated. Here is the code:
Public Sub LoopRows(Appserver As String, StartTime As Date, EndTime As Date)
Dim x As Integer
Dim NumROws As Integer
NumROws = Range("Sheet3!C5").End(xlDown).Row - Range("Sheet3!C5").Row
Worksheets("Sheet3").Activate
Range("Sheet3!C5").Select
msgbox Appserver
msgbox StartTime
msgbox EndTime
For x = 1 To NumROws
ActiveCell.Offset(1, 0).Select
If (ActiveCell.Offset(0, 1).Value = Appserver) Then
Dim RowStartTime As Date
Dim RowEndTime As Date
msgbox ActiveCell.Offset(0, 1).Value
msgbox RowStartTime = Val(ActiveCell.Offset(0, 3).Value)
msgbox RowEndTime = Val(ActiveCell.Offset(0, 4).Value)
If (((EndTime > RowStartTime) And (EndTime < RowEndTime)) Or (((StartTime > RowStartTime) And (StartTime < RowEndTime))) Or (((StartTime < RowStartTime) And (EndTime > RowEndTime)))) Then
msgbox "Conflict"
Else
msgbox "noConflict"
End If
End If
Next
End Sub

Answer 1

Simplify your If condition. It's impossible for two time spans to overlap without one starting time falling between the other span's start and end:
Partial overlap case:
Start1 End1
|----------------------------|
Start2 End2
|---------------------|
Complete overlap case:
Start1 End1
|----------------------------|
Start2 End2
|----------------|
You can make the If condition this:
If (StartTime > RowStartTime) And (StartTime < RowEndTime) Or _
(RowStartTime > StartTime) And (RowStartTime < EndTime) Then
Edit: It should look more like the code below. Note that I'm assuming from the original code that the "Appserver" value is in column "F", starting times are in column "H", and ending times are in column "I". There is also no error checking on the CDate calls (but then again there wasn't on the Val calls either).
Public Sub LoopRows(Appserver As String, StartTime As Date, EndTime As Date)
Dim CurrentRow As Integer, LastRow As Integer
Dim RowStartTime As Date, RowEndTime As Date
With Worksheets("Sheet3")
LastRow = .Range("C" & .Rows.Count).End(xlUp).Row
For CurrentRow = 6 To LastRow
If (.Cells(CurrentRow, 6).Value = Appserver) Then
RowStartTime = CDate(.Cells(CurrentRow, 8).Value)
RowEndTime = CDate(.Cells(CurrentRow, 9).Value)
If (StartTime > RowStartTime) And (StartTime < RowEndTime) Or _
(RowStartTime > StartTime) And (RowStartTime < EndTime) Then
MsgBox "Conflict"
Else
MsgBox "noConflict"
End If
End If
Next
End With
End Sub