ok sono riuscito a eliminare l'errore (bastava riscrivere le variabili tra parentesi)
adesso con
B4X:
Sub pnlCanoista_Touch (action As Int, x1 As Float, y1 As Float) As Boolean
If action = Activity.ACTION_DOWN Then
PositionX = x1
PositionY = y1
cnvCanoista.DrawCircle(x1,y1,20dip,Colors.Red,False,5dip)
cnvCanoista.DrawPoint(x1,y1,Colors.Red)
ToastMessageShow("OK",False)
Activity.Invalidate
'Msgbox("You touched at X = " & x1 & " Y = " & y1,"test")
End If
Return
End Sub