Grid filter

[Curious]

In my grid, there's a column called 'Time Scanned', which is an alias
for a column in a table, i.e.,
DistributionPri ntReceiptInstan ce.ReceiptTime.

I want to use 'Time Scanned' column as a filter as below:

lFilters.Add(ne w GenericFilter(" Not Yet Scanned", "'Time
Scanned' IS NULL", true));

However, this doesn't work. I guess something is wrong with the
syntax.

I also tried the following:

lFilters.Add(ne w GenericFilter(" Not Yet Scanned",
"DistributionPr intReceiptInsta nce.ReceiptTime IS NULL", true));

Again, this doesn't work. Any advice? Thanks!