Your syntax is incorrect - you need to read up on ADO.NET.

If you use a DataReader which is forward only, you generally populate your
own business object (not datasets) as you have to read through the database
sequentially.

You are getting the DataSet and DataReader mixed up. When you use a
DataAdapter, you generally use DataSets. When you use the Fill method, you
fill a DataSet object, not a DataReader.

When you create the DataAdapter you need to assign it a SqlConnection
object, your code isn't doing this.

Another tip, using a DataAdapter you don't need to open and close the
connection, the DataAdapter does this for you automatically. If using a
DataReader - always remember to close it afterwards.

So try changing your code to something like:

                connect = new
                System.Data.SqlClient.SqlConnection(connectString);
               

                System.Data.Common.DataAdapter da = new
System.Data.Common.DataAdapter("SELECT *
FROM "+owner+tableName+ " WHERE "+ tableField+ " IN("+inClause+")",connect);
        DataSet mySet = new DataSet("Myset");

                da.Fill(mySet);

I'd recommend using the Data Access Block from the Client Software Factory,
it makes database coding so much easier. I had to scratch my head to answer
this post as I can bearly remember ADO now that I use the data application
block.