Getting runtime error when sub executed through userform change rather than directly

[drew.j.harrison]

So I developed some code that hides/unhides certain rows based on selections on a userform. I want it to run when a change is made to one of the userform fields that affects what should be visible. The code seems to work great when I execute the macro directly however when I set the userform to call the macro when a change is made to the userform I get an error on the line where it defines the row the selected part number is listed ("PartNumberRow"). The specific error is "Run-time error '1004': Application-defined or object-defined error". What the heck am I missing here. Why would it run just fine when executed directely but not when it is called by a userform change. Thanks for all the help.

Sub Hide_Show_Parts_And_Info()
'Show Only Selected Part Information and Parts
Application.ScreenUpdating = False
    If User_Controls.View_Part.Value = "" Then
        Application.ScreenUpdating = True
        Exit Sub
    Else
        Dim PartNumber As String
        Dim PartNumberRow As Long
        PartNumber = User_Controls.View_Part.Value
        Sheets("Imported Bid").Activate
        PartNumberRow = Range("Test_Range").Find(What:=PartNumber).Row
        Dim Range1Top, Range2Top, Range1Bottom, Range2Bottom, Range1, Range2 As Range
        
        Set Range1Top = Cells(7, 1)
        Set Range1Bottom = Cells(PartNumberRow - 1, Range1Top.Column)
        
        Set Range2Top = Cells(PartNumberRow + 41, 1)
        Set Range2Bottom = Cells(1300, Range2Top.Column)
        
        Set Range1 = Range(Range1Top, Range1Bottom)
        Set Range2 = Range(Range2Top, Range2Bottom)
           
        If PartNumberRow = 7 Then
            Range2.EntireRow.Hidden = True
        Else
            Range1.EntireRow.Hidden = True
            Range2.EntireRow.Hidden = True
        End If
    End If
Application.ScreenUpdating = True
End Sub

 

[Andrew Poulsom]

Do you need to convert the string PartNumber to a number - Val(PartNumber)?

 

[drew.j.harrison]

The "PartNumber" is actually text not a number.

 

[Andrew Poulsom]

You're missing a few of Find's arguments. Maybe they are set wrongly. What's saved between calls is list in VBA Help.