using class module properties in UDF's excel vba - class

Question

I have the following function that works fine:
Function GetAgentEmailWorksheet(AgentObjectId As String)
Dim specific_agent As clsAgent
Set specific_agent = New clsAgent
specific_agent.AgentSheetName = "agentsFullOutput.csv"
Dim id_array() As Variant
id_array = specific_agent.AgentIDArray
Dim email_array() As Variant
email_array = specific_agent.AgentEmailArray
GetAgentEmailWorksheet = vlook_using_array(AgentObjectId, id_array, email_array)
End Function
When, however, I change the last line to:
GetAgentEmailWorksheet = vlook_using_array(AgentObjectId, specific_agent.AgentIDArray, specific_agent.AgentEmailArray)
I get the following error:
Compile error:
Type mismatch:array or user-defined type expected
and it hi-lights AgentIDArray (or AgentEmailArray if I sub out the first parameter.
Why?
EDIT
here's the fuction vlook_using_array:
Function vlook_using_array(target_string As String, _
input_array() As Variant, _
output_array() As Variant)
Dim rows_dim As Long
Dim cols_dim As Integer
For rows_dim = 1 To UBound(input_array, 1)
For cols_dim = 1 To UBound(input_array, 2)
If input_array(rows_dim, cols_dim) = target_string Then
vlook_using_array = output_array(rows_dim, cols_dim)
End If
Next cols_dim
Next rows_dim
End Function
Here are the clsAgent properties:
Public Property Get AgentClientsArray() As Variant
AgentClientsArray = get_column_array(AgentClientsCol)
End Property
Public Property Get AgentIDArray() As Variant
AgentIDArray = get_column_array(1)
End Property
Public Property Get AgentEmailArray() As Variant
AgentEmailArray = get_column_array(AgentEmailCol)
End Property
Here's the function that's in the class module:
Private Function get_column_array(col_num As Integer) As Variant
' create a range out of the used range (of the sheet) in the column specified
' used to create array properties in the class
Dim total_rows As Long
total_rows = Worksheets(Me.AgentSheetName).UsedRange.rows.Count
Dim target_range As Range
With Worksheets(Me.AgentSheetName)
Set target_range = .Range(.Cells(1, col_num), .Cells(total_rows, col_num))
End With
Dim target_arr() As Variant
target_arr = target_range
get_column_array = target_arr
End Function

Answer 1

There's a difference between this:
Public Property Get AgentIDArray() As Variant
AgentIDArray = get_column_array(1)
End Property
and
Public Property Get AgentIDArray() As Variant()
AgentIDArray = get_column_array(1)
End Property
The first (which you have in your class) returns a Variant which happens to be an array, the second an array of variants.
So, the return value of your AgentIDArray is not consistent with the parameter types expected by vlook_using_array