Asp.net - Adding Textbox To Modal Popup Stopped Allowing INSERTS?

I have a modal popup that allows an admin to choose from a variety of checkboxes to add features to a specific product. If there is a checkbox that an admin believes should be available but isn't because that feature is not in the database, I have added a textbox so that user can add a new feature to the product.

Once I added the textbox, it stopped allowing inserts. At first it was in the same If Else as the checkbox for each loop, but I have recently changed it so the textbox is in it's own for each loop. I have an underline under the words txtFeature.Text that says Value of type 'Char' cannot be converted to 'System.Web.UI.WebControl.Textbox.'

vb code:

For Each feature As ListItem In cbxAddFeature.Items
If feature.Selected Then
Dim strSQL As String = "INSERT INTO Marketing

[code]....