For Loop Combo Boxes with If Statement

Hi, I am a beginner to VBA looking for some help with a For Loop

I have a Userform with 18 Comboboxes named mid1, mid2, mid3 etc which would hold an item description and then 18 textboxes named mia1, mia2, mia3 etc which would hold corresponding currency amount (There are other textboxes on the userform as well)

On Userform Activate, I am trying to disable a mia textbox if the corresponding mid combobox is empty.

eg if mid3 is empty then mia3 needs to be Disabled.

This is what I have got so far:

Private Sub UserForm_Activate() 

Dim coll As New Collection
    Dim item As TextBox
    Dim i As Integer

    coll.Add Me.mia1
    coll.Add Me.mia2
    coll.Add Me.mia3
    coll.Add Me.mia4
    coll.Add Me.mia5
    coll.Add Me.mia6
    coll.Add Me.mia7
    coll.Add Me.mia8
    coll.Add Me.mia9
    coll.Add Me.mia10
    coll.Add Me.mia11
    coll.Add Me.mia12
    coll.Add Me.mia13
    coll.Add Me.mia14
    coll.Add Me.mia15
    coll.Add Me.mia16
    coll.Add Me.mia17
    coll.Add Me.mia18
    
Set i = 1
With i
    For Each item In coll
        If Me.Controls("mid" & i).text = ""
    Then
        item.Enabled = False
        item.BackColor = vbGrey
        i = i + 1
        Next item
        
    End With
End Sub

I keep getting a compile error when i is set to 1, where am I going wrong.

Also is a for loop the best way to achieve this?

Many thanks for all help.