access .findfirst method syntax

I have a .findfirst method in my function but it squeels error 3251 op is not supported

not sure how to correct.

Public Function ApplyAlias(Strin As String) As String


Dim Db As DAO.Database
Set Db = CurrentDb()
Dim rstTclient As DAO.Recordset
Dim StrOutput As String
Dim Index As Integer

Dim WordArray() As String
WordArray() = Split(Trim(Strin), " ")
Set rstTclient = Db.OpenRecordset("TblModelAlias")

For Index = LBound(WordArray) To UBound(WordArray)

    With rstTclient
        .MoveFirst
        
        .FindFirst "[sDesc] = '" & WordArray(Index) & "'"
          If .NoMatch Then
          'do nothing
          Else
            WordArray(Index) = .Fields("sClientDescGroup").Value
          
          End If
    
    End With
    
Next

Index = 0

For Index = LBound(WordArray) To UBound(WordArray)

If Index = 0 Then

    StrOutput = WordArray(Index)

Else
    StrOutput = StrOutput & " " & WordArray(Index)
End If
   
Next


ApplyAlias = StrOutput





End Function

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