Relations + ADO.NET ?[Resolved]

[Pirate]

I'm getting this error that says : "This constraint cannot be enabled as not all values have corresponding parent values "


I'm getting data from two relational tables . Hmm , have a look at the code .

How can I solve this problem ?

public void ShowInGrid()
{
DataSet ds;
//two commands for MainCat_Tab & SubCat_Tab tables
System.Data.OleDb.OleDbCommand cmd;
System.Data.OleDb.OleDbCommand cmd2;

//two adapters for filling ds obj
System.Data.OleDb.OleDbDataAdapter adp;	
System.Data.OleDb.OleDbDataAdapter adp2;


//this handles the relationship between 
//the two columns 
System.Data.DataRelation datarelation;
System.Data.DataColumn dc1;
System.Data.DataColumn dc2;
				

ds =new DataSet();
ds.CaseSensitive=true;
//First command for first table
cmd=new OleDbCommand ();
cmd.Connection=DBSpace.FunctionClass.MyConnection;
cmd.CommandText="SELECT * FROM MainCat_Tab";

//Second command for Second table
cmd2=new OleDbCommand ();
cmd2.Connection=DBSpace.FunctionClass.MyConnection;
cmd2.CommandText="SELECT * FROM SubCat_Tab";

//first table
adp=new OleDbDataAdapter ();
adp.SelectCommand =cmd;
adp.TableMappings.Add("Table","MainCat_Tab");
adp.Fill(ds);

			
//Second table
adp2=new OleDbDataAdapter ();
adp2.SelectCommand=cmd2;
adp2.TableMappings.Add ("Table","SubCat_Tab");
adp2.Fill(ds);

dc1=ds.Tables["MainCat_Tab"].Columns["MainCat_ID"];
			dc2=ds.Tables["SubCat_Tab"].Columns["SubCat_ID"];
datarelation=new System.Data.DataRelation("MainCat_TabToSubCat_Tab",dc1,dc2);

ds.Relations.Add (datarelation);
			
Here is the error  dataGrid1.DataSource=ds;//.DefaultViewManager;
dataGrid1.DataMember="MainCat_Tab";
}