restrict null in column??

Hi,

I'm trying to design a database and am trying to restrict the use of null values in the columns. When I create the column and check the box to restrict the null values, I can't save it. It gives me this error:

-2147467259: error while executing the query;
ERROR: adding not null columns is not implemented. Add the column, then use Alter Table Add Constraint.

In pgAdmin, you can view the column properties after you saved it, but can't change the null value state. Am I doing something wrong? do I have an old version or is this just another Postgres issue that I have to work around?

Thanks
James Newman
Castleberry Investments