receiving "out of range" error, can't figure out why - vba

Question

Let me start by first thanking everyone for the help/intention to help. This community is phenomenal. Second: I'm pretty new at this- before this week I'd learned basic in highschool a decade ago but no other programming experience outside of theory.
Without further ado, here's my issue:
Working on code to find unique variables (I know there's a lot of opensource stuff out there, need to customize this though). When I go to populate the array with the very first string I run into an 'out of range' error at array(1), which I had explicity set (1 TO UB), with UB being the upper bound. I've also double checked the value of UB with msgbox and it's at 15 with my dummy data, so that shouldn't be an issue. I've set the values in the array to empty (have also done so with 0, to no avail).
The error occurs at "ResultArray(1) = CurrentArray(1)"
I'm at a loss; any assistance would be much appreciated.
Option Explicit
Sub unque_values()
'''''''''Variable declaration
'
' CurrentArray() is the array taken from the worksheet
' Comp is the method of comparing inputs (either case sensitive or case insensitive)
' resultarray() is the array that unique values are placed
' UB is the upper bound of Result Array
' resultindex is the variable that keeps track of which cells are unique and which are not
' n is a helped variable that assists with resizing the array
Dim currentarray() As Variant
Dim comp As VbCompareMethod
Dim resultarray() As Variant
Dim UB As Long
Dim resultindex As Long
Dim n As Long
Dim v As Variant
Dim inresults As Boolean
Dim m As Long
' set variables to default values
Let comp = vbTextCompare
Let n = 0
' count the number of cells included in currentarray and populate with values
Let n = ActiveWorkbook.Worksheets("Data").Range("A:A").Count
Let UB = ActiveWorkbook.Worksheets("Data").Range("A" & n).End(xlUp).Row
' dimension arrays
ReDim resultarray(1 To UB)
ReDim currentarray(1 To UB)
' don't forget to change to named ranges
Let currentarray() = Range("f2", "f" & UB)
' populate resultarray with empty values
For n = LBound(resultarray) To UBound(resultarray)
resultarray(n) = Empty
Next n
MsgBox (n)
'check for invalid values in array
For Each v In currentarray
If IsNull(n) = True Then
resultarray = CVErr(xlErrNull)
Exit Sub
End If
Next v
' assumes the first value is unique
resultindex = 1
'''''''''''''''''''''''''''''''''''''''''error is this line''''''''''''''
resultarray(1) = currentarray(1)
' Search for duplicates by cycling through loops
' n = index of value being checked
' m = index of value being checked against
For n = 2 To UB
Let inresults = False
For m = 1 To n
If StrComp(CStr(resultarray(m)), CStr(currentarray(n)), comp) = 0 Then
inresults = True
Exit For
End If
Next m
If inresults = False Then
resultindex = resultindex + 1
resultarray(resultindex) = currentarray(n)
End If
Next n
ReDim Preserve resultarray(1 To resultindex)
End Sub

Answer 1

You've assigned to currentArray a range array. These are always two-dimensional arrays.
You should be able to resolve it with:
resultarray(1) = currentarray(1, 1)
You would need to modify a few more lines in your code to refer to both dimensions of the array.
Alternatively, with the least manipulation to your existing code, transpose the array which turns it to a one-dimensional array. This should require no other changes to your code.
Let currentArray() = Application.Transpose(Range("f2", "f" & UB))

Answer 2

Try with ActiveWorkbook.Worksheets("Data").UsedRange.Columns(1).cells.Count