VBA across Access and Excel

I am currently writing a VBA macro in Access which opens and uses an Excel spreadsheet to import certain pieces of data. I am trying to use the Find method to find a piece of text in the Excel spreadsheet and, using the range returned, obtain the row that the piece of text is in (I know that there is only one instance of the text in the spreadsheet).

However, I receive a Compile error: User-defined type not defined on the Range variable which I have set to hold the result of the Find method. Is this because Access and Excel have different find methods? Or because I am trying to run an Excel VBA method from Access VBA?

I would be grateful if you would let me know if I am doing something wrong, or whether there is anyother way of achieving my purpose (ideally without using a for loop). I have attached a snippet of my code below which hopefully will show what I am doing.

Many thanks,

Monique

NOTE: xl is an Object variable holding the Excel application and spreadsheet to copy data from. Any undeclared variables are Public variables declared in the main module.

Private Sub Main2UploadTAs()

Dim UnitRange As Range
Dim UnitRow As Integer
Dim Column As Integer

xl.Sheets(1).Select
' The rows of data start at row 21
Row = 21
' While there is a new row of data
Do While Not IsEmpty(xl.Cells(Row, 11))
' Select the plant
Plant = xl.Cells(Row, 3)
' Select the data for that unit for that year
TAssay = xl.Cells(Row, 11)
*
This is the section of code which I am having problems with
*
' Select the sheet to search in
xl.Sheets("UNITS").Select
' Find the cell which contains the text in the Plant string
Set UnitRange = xl.Cells.Find(What:=Plant, After:=xl.Cells(1, 1), LookIn:=xl.xlValues, LookAt:= _
xl.xlPart, SearchOrder:=xl.xlByRows, SearchDirection:=xl.xlNext, MatchCase:=False _
, SearchFormat:=False)

UnitRow = UnitRange.Row
*
The code from this point on works
*
' The first unit ID is in column 5
Column = 5
Do While Not IsEmpty(xl.Cells(UnitRow, Column))
' Select the unit ID
UnitID = xl.Cells(UnitRow, Column)
' Update the record in the database
DoCmd.RunSQL "UPDATE ProductionUnitAssayCalendar SET [Assay]=" & TailsAssay & " WHERE [ProductionUnitId]=" & UnitID & " AND [TypeId]=1 AND [StartDate]=#01/01/" & Year & "#;"
' Move across the list of units
Column = Column + 1
Loop
' Move down the list of plants
Row = Row + 1
Loop
Next Year

End Sub