Hierarchical Webgrid

[kaytejt]

I have two procedures that call when I do a databind. I want these
two procedures to be populated in a parent child relationship in a
hierarchical webgrid. However, all the examples that I have seen are
using oledbdataadapters to combine two tables, but I cannot use this
in my case because I am pulling stored procedures that pull back
datasets.

ds = contractUnderwriting.GetCUPipeline(statusValue, Profile.OrgId)
ds1 = contractUnderwriting.GetCUPipelineFilter(statusValue,
Profile.OrgId)

and when I do the relation

dsFinal.Relations.Add(ds.Tables(0).Columns("WORKOBJNUM"),
ds1.Tables(0).Columns("WORKOBJNUM"))

the error reads "Object reference not set to an instance of an
object."

Any suggestions?