Subreport fields empty

Question

I made a subreport to header of 2 other crystal report. one of the main reports are filled well, but the second remain empty. I fill the sub in the same way.

rowTest("field1") = "123" ' rowTest = dtTest.NewRow
dtTest.Rows.Add(rowTest) 
ds.Tables.Add(dtTest) ' this is the dataset

Main report:

crTest.SetDataSource(ds) ' in debug I see ds contains all fields

Subreport:

ds.Tables.Clear() ' clear all the dataSet 
Dim dtTest As New ds.dtTestDataTable ' instanse of data table 
Dim rowTest As DataRow = dtTest.NewRow ' create row

I tried to re-import the subReport but nothing happened. Any ideas?