Error "object reference not set to instance of an object" when trying to set datasource property of a bound column in datagrid control

[Martin Widmer]

Hello again!

I have a datagridview control on my form and am using VS.Net 2005. One
column is set up as combo box column, and when I try to set the datasource
for that combobox column at design time in the properties section of VS, I
get the error "object reference not set to instance of an object" and the
only option is to click OK.

I have not yet tried to set that datasource at runtime, but of course I
could do that. But I don't understand why now I cannot do it at design time,
while I could do it with another datagridview on the same form! Any hints?

For the binding I have set up a bindingsource object already...

Martin