How To Specify Data Type For Datacolumn In Vb.net?

[MeDontGetSomething]

The thing is I'm currently working with Infragistics NetAdvantage UltraGrid and I use DataSet with one table as DataSource. Since data dosen't come straigh from database i have to make columns of that table manually so i just use Add method and only give column name as paramter.

For some reason when i try to change value in grid from number to nothing the grid gives me message that "Unable to update the data value: Cast from string "" to type 'Long' is not valid"! Where the Long came from? Somekind of default i donno.

P.S. I know that you can specify type when you create column but... when I wrote something like:

 dsDataset.tables(0).add("name",string) 

there happens to be an error in there.

Anyway please help.