(VB) Spawning multiple enemies - vb.net

Question

I'm currently making an arcade shooting game in Visual Basic which spawns enemies at the top of the form which move vertically downward toward the player. My current code spawns the enemy, but any attempt to add another 'enemyShip' to the 'enemyShips' array fails and hence, only a single enemy is spawned. Any help as to how to spawn multiple enemies would be appreciated. My current code is below:
Dim enemySize As Integer = 32
Dim enemySpawn As New Point(150, 0)
Dim enemyShip As New Rectangle(150, 0, enemySize, enemySize)
Dim enemyLoc As New Point(enemyShip.Location)
Dim enemySpr As Image = My.Resources.sprEnemy32x32
Dim enemySpeed As Integer = 5
Dim enemyShips(-1) As Rectangle
Dim intCount As Integer = 0
Dim g, bbg As Graphics
Dim backBuff As Bitmap
Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
g = Me.CreateGraphics
backBuff = New Bitmap(300, 300, Imaging.PixelFormat.Format32bppPArgb)
bbg = Graphics.FromImage(backBuff)
tmrSpawn.Enabled = True
tmrRender.Enabled = True
End Sub
Private Sub tmrSpawn_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrSpawn.Tick
SpawnEnemy()
End Sub
Private Sub SpawnEnemy()
'Add enemyShip to index in array enemyShips
'Add 1 to enemyShip's index so new rectangle is stored in the next index
ReDim Preserve enemyShips(intCount)
enemyShips(intCount) = enemyShip
intCount += 1
'Move newly created enemyShip vertically downward on the form
For Each Me.enemyShip In enemyShips
enemyLoc = New Point(enemyShip.Location.X, enemyShip.Location.Y + enemySpeed)
enemyShip.Location = enemyLoc
Next
End Sub
Private Sub tmrRender_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrRender.Tick
bbg.DrawImage(enemySpr, enemyShip)
g.DrawImage(backBuff, 0, 0)
bbg.Clear(Color.Gray)
End Sub