Text='<%# Bind("CheckDate", "{0:MM/dd/yyyy}") %>'
must work
codebehind (IMO ToShortDateString , Bind("CheckDate", "{0:MM/dd/yyyy}"):
Private Sub FormView1_DataBound(ByVal sender As Object, ByVal e As System.EventArgs) Handles FormView1.DataBound
Select Case FormView1.CurrentMode
Case FormViewMode.Edit
Dim dr = DirectCast(FormView1.DataItem,DataRowView)
Dim TextBox1 = DirectCast(FormView1.FindControl("TextBox1"), TextBox)
Dim CheckDate = DirectCast(dr("CheckDate"), Date)
TextBox1.Text = CheckDate.ToShortDateString()
End Select
End Sub