Problem in UPDATE query in GridView

[Saber]

I have a gridview:

<asp:GridView ID="GridView1" runat="server" AllowPaging="True"
AllowSorting="True" AutoGenerateColumns="False" CellPadding="4"
DataSourceID="SqlDataSource1" ForeColor="#333333" GridLines="None"
DataKeyNames="ADid">

and it is my update query:

UPDATE tblAds SET ADName = @ADname, ADType = @ADType, ADPriority =
@ADPriority FROM tblAds INNER JOIN tblCategories ON tblAds.ADCatID =
tblCategories.CatID WHERE tblAds.ADid = @ADid

When I try to update a field, I get an error message:
Must declare the variable '@ADid'.

 

[Saber]

no idea?