may be coonected table not filled by adapter?
Of course it is. I re-explain:
 m_dsFields = GetReportFields(1)
'here m_dsFields.tables(0) contain correct data
 PrepareColumn()
 FlyGrid1.Rows.DataMember = m_dsFields.Tables(0).TableName
 FlyGrid1.Rows.DataSource = m_dsFields
does not work
 m_dsFields = GetReportFields(1)
'here m_dsFields.tables(0) contain correct data
dim dt as datatable = m_dsfields.tables(0)
 PrepareColumn()
 FlyGrid1.Rows.DataMember = dt.tablename
 FlyGrid1.Rows.DataSource = dt 
works.
I can' t see any difference or explain why it works if i use a tmp datatable....
I will assume the problem is on our side then.... 
Can you have a look at my other questions please
Thanks