Range selection

Hello world,

I am quite new to vba and I am trying to build a 3 step macro that will

1- separate values ("deconcatenate them") from a given column in a different location on the same sheet
2-Filter these values so that I get a list of unique values
3-Count the occurences of each unique value

The macro is quite simple, i actually did not write it myself except for step 2. And the glitch is in... step 2.

Sub PieChartCommodityInvolved()
'
'PieChartCommodityInvolved Macro
'1-Converts each value from column P in a distinct column (Z and next columns)
'2-Filtrates the (Z,...) range so that each type of commodity appears once in column AI
'3- Computes the number of occurences of each commodity in AJ

 Dim i As Long
 
'1
    Sheets("Data input").Select
    Range("P3:P300").Select
    Selection.TextToColumns Destination:=Range("Z3"), DataType:=xlDelimited, _
        TextQualifier:=xlDoubleQuote, ConsecutiveDelimiter:=False, Tab:=False, _
        Semicolon:=True, Comma:=False, Space:=False, Other:=False, FieldInfo _
        :=Array(1, 1), TrailingMinusNumbers:=True
'2
   Range("Z3").Select
   For i = 0 To 65536
   i = i + 1
   Range(Selection, Range("Z2").Offset(0, i).EndToRight).Select
   Next i
   Selection.AdvancedFilter Action:=xlFilterCopy, CopyToRange:=Range("AI"), Unique:=True
        
'3
    Range("AJ4").Select
    ActiveCell.FormulaR1C1 = "=COUNTIF(R[-1]C[-9]:R[296]C[-2],RC[-1])"
    Range("AJ4").Select
    Selection.AutoFill Destination:=Range("AJ4:AJ300"), Type:=xlFillDefault
    Range("AJ4:AJ300").Select
End Sub

At line

Range(Selection, Range("Z2").Offset(0, i).EndToRight).Select

i am returned the error "438, method does not support this object"
The thing is that i am trying to select only the non-void cells to filter them.

Big love for your help !!