Empty a field by datasource

Hi there,

I've got a matrix with some columns. I've got userdatasources bound to them. So far, so good.

One of those userdatasources is of the type <i>dt_SHORT_NUMBER</i> and bound to a column. Now do I want to place a empty value in a certain field in the column this datasource is bound to, using the datasource.

<b>Code (C#)</b>

for(int i = 1; i <= oMatrix.RowCount; i++)
{
  oMatrix.GetLineData(i);
  oDataSource.ValueEx = "";
  oMatrix.SetLineData(i);
}

But this gives me an error... (Data Source - Invalid field value)

Does anybody have a solution?