System.Data.SqlClient.SqlException: Incorrect syntax near '=

Question

DropDownList4.Items.Clear()

DropDownList4.Items.Add("--Select City--")

Dim st As String

st = "select * from tbl_city where State_ID=" + DropDownList3.SelectedItem.Value

Dim cm As New SqlCommand(st, con)

Dim da As New SqlDataAdapter(cm)

Dim d As New DataTable()

da.Fill(d)

DropDownList4.DataSource = d

DropDownList4.DataBind()

 

 

 

this is my code  i got error 

Incorrect syntax near '='.

please help me  

 

i got error at this line

da.Fill(d)

 

thanks in advance

please reply fast

i really want help