Match Index Issue in VBA - vba

Question

I have the following code. The Loop seems to function well but the ColNum and RowNum lines are only creating 0's the data up to this point is filled out so a blank isn't causing the issue
If Sheets("Control").Range("B6") = "#.#" Then
For i = 1 To ColACount - 2
If FullData(i, 3) <= Sheets("Control").Range("B5") _
And FullData(i, 3) >= Sheets("Control").Range("B4") Then
ColNum = WorksheetFunction.Match(FullData(i, 1), Application.Index(RetGross, 1), 0)
RowNum = WorksheetFunction.Match(FullData(i, 3), Application.Index(RetGross, , 1), 0)
If RetGross(RowNum, ColNum) = "" Then 'Prevents overwriting
RetGross(RowNum, ColNum) = FullData(i, 4)
End If
End If
Next i
End If
I have used Application.Worksheetfunction on the Index and then it really crashes.
Edit: All Code
Sub TransferData()
'Declarations
Dim ReturnWB As String 'File name from Investment metrics
Dim ReturnWBtab1 As String
Dim ReturnWBtab2 As String
Dim ReturnWBtab3 As String
Dim ColACount As Integer 'Total data in column A of Return Puller
Dim FullDataP As Variant ' Pulling data
Dim FullData As Variant ' Building Matrix
Dim Names As Variant
Dim Unique As Integer 'Total Number of unique names
Dim Months As Integer 'Months Specified
Dim StartYear As Integer
Dim EndYear As Integer
Dim StartMonth As Integer
Dim EndMonth As Integer
Dim RetGross As Variant 'Tab data
Dim RetNet As Variant 'Tab data
Dim MValues As Variant 'Tab data
Dim Corner As String 'set the corner value for pasting the array
Dim ColNum As Integer 'Dynamic variable to update matrix
Dim RowNum As Integer 'Dynamic variable to update matrix
Dim First As Integer 'First row for shading - Dynamic and changing
Dim Inceptions As Variant 'Inception Dates
Dim BotRow As Integer 'Testing for Gaps
Dim TopRow As Integer 'Testing for Gaps
'Call Clearing
Workbooks("Return Formatter - Investment Metrics.xlsm").Activate
'Setting Names
ReturnWB = Sheets("Control").Range("B3") & ".xls" 'Excel Name
ReturnWBtab1 = "Pre Fee Returns" 'Tab Name
ReturnWBtab2 = "After Fee Returns" 'Tab Name
ReturnWBtab3 = "Total Fund Market Value" 'Tab Name
'Error Control
On Error GoTo Err1
'Prepping the Dates and Name
StartYear = Year(Sheets("Control").Range("B4"))
EndYear = Year(Sheets("Control").Range("B5"))
StartMonth = Month(Sheets("Control").Range("B4"))
EndMonth = Month(Sheets("Control").Range("B5"))
Months = (EndYear - StartYear + 1) * 12 - (StartMonth - 1) - (12 - EndMonth)
'Find all the unique names/managers and list them
ColACount = WorksheetFunction.CountA(Workbooks(ReturnWB).Sheets(ReturnWBtab1).Range("B:B"))
'Building a Matrix
FullDataP = Workbooks(ReturnWB).Sheets(ReturnWBtab1).Range("B2:E" & ColACount)
FullData = FullDataP
ReDim Preserve FullData(1 To (ColACount - 1), 1 To 5)
'Adding Start Date
FullData(1, 5) = FullData(1, 3)
For i = 2 To (ColACount - 1)
If FullData(i, 1) = FullData(i - 1, 1) Then
FullData(i, 5) = FullData(i - 1, 5)
Else
FullData(i, 5) = FullData(i, 3)
End If
Next i
ReDim Names(1 To 3, 1 To ColACount - 1) 'Setting max size
Names(1, 1) = FullData(1, 1) ' loading first value
Names(2, 1) = FullData(1, 5) ' loading first value
Names(3, 1) = 1 'Tracking the count
x = 1
For i = 1 To (ColACount - 2)
If Names(1, x) <> FullData(i + 1, 1) Then
Names(1, x + 1) = FullData(i + 1, 1)
Names(2, x + 1) = FullData(i + 1, 5)
Names(3, x + 1) = 1 'Tracking the count
x = x + 1
End If
Next i
Unique = WorksheetFunction.Sum(Application.Index(Names, 3)) 'Number of MGRs/Names
ReDim RetGross(1 To Months + 1, 1 To (Unique + 1)) 'Setting Size
ReDim Inceptions(1 To 1, 1 To (Unique + 1)) 'Setting Size
Inceptions(1, 1) = "Inception Date ->"
'Building Dates
For i = 1 To Unique
Inceptions(1, i + 1) = Names(2, i)
Next i
Corner = Sheets("ReturnsGross").Range("A2").Offset(0, Unique).Address
'Dropping Dates
Sheets("ReturnsGross").Range("A2:" & Corner) = Inceptions
'Sheets("ReturnsNet").Range("A2:" & Corner) = Inceptions
'Sheets("MarketValues").Range("A2:" & Corner) = Inceptions
RetGross(1, 1) = "Manager Name ->"
RetGross(2, 1) = WorksheetFunction.EoMonth(DateSerial(Year(Sheets("Control").Range("B4")), Month(Sheets("Control").Range("B4")), 1), 0)
'Building Dates
For i = 1 To Months - 1
RetGross(i + 2, 1) = WorksheetFunction.EoMonth(RetGross(i + 1, 1), 1)
Next i
'Building Names
For i = 1 To Unique
RetGross(1, i + 1) = Names(1, i)
Next i
'RetNet = RetGross 'These Lines will have to change
'MValues = RetGross 'These Lines will have to change
'Code to here function correctly
'Grabbing Data Gross
'Grabbing Data
If Sheets("Control").Range("B6") = "#.#" Then
For i = 1 To ColACount - 2
If FullData(i, 3) <= Sheets("Control").Range("B5") And _
FullData(i, 3) >= Sheets("Control").Range("B4") Then
ColNum = WorksheetFunction.Match(FullData(i, 1), Application.Index(RetGross, 1), 0)
RowNum = WorksheetFunction.Match(FullData(i, 3), Application.Index(RetGross, , 1), 0)
If RetGross(RowNum, ColNum) = "" Then 'Prevents overwriting
RetGross(RowNum, ColNum) = FullData(i, 4)
End If
End If
Next i
End If