Lookup Sunset Time Based Onrecord Date - Incorrect Time Calculated

Consider this code:

'light eligibility
Dim facb As String
Dim sunset As Variant
[color=green]' check if facility has lights[color]
facb = WorksheetFunction.VLookup(RID, ds, 10, False) 'find facility code
If WorksheetFunction.VLookup(facb, fac, 6, False) = "Y" Then 'facility has lights
sunset = WorksheetFunction.VLookup(tempws.Range("A9"), sun, 2, False) 'lookup the sunset time based on the record's date

[Code] ......

This code checks the need for lights at a facility.

It first checks to see if the facility even has lights by cross-referencing a value in the record with a facilities database.

If it has lights, it then checks to see if they are needed. If the rental goes past the sunset time, then it needs lights. Sunset is determined by cross-referencing the date value in sheet1! A9, with the sunset database.

If it needs lights, variable lghtson is calculated equal to "sunset"-30 minutes.

As I step through this code:

WorksheetFunction.VLookup(facb, fac, 6, False) = "Y" Facility has lights.
Check to see if lights are needed.
sunset = WorksheetFunction.VLookup(tempws.Range("A9"), sun, 2, False)
sunset=0.879166666666667 which is 9:06PM. This is a proper value from the lookup.
If rental_end.value > sunset Then
rental_end (value from textbox) = "9:30 pm" , sunset=0.879166666666667. This is true, and Excel accepts it as true ...
lghtson = sunset - 0.5
0.379166666666667 = 0.879166666666667 - 0.5 (9:06 AM)

This is not the value I was looking for. I was looking for 8:34PM (0.856944444444444)