Cannot use stratified sampling

I cannot use the “Stratified sampling” option in the Row Sampling node. The option will not light up.

The other options are available and work. My table has several numbers and no text elements.

Are there any limitations on which table types (metadata) can support stratified sampling? Do I need a nominal column?

This is a really cool program. Thanks very much!

Both Knime 2.0.3 and 2.1.0
Windows Vista 64-bit
$ java -version
java version "1.6.0_14"
Java™ SE Runtime Environment (build 1.6.0_14-b08)
Java HotSpot™ 64-Bit Server VM (build 14.0-b16, mixed mode)

For stratified sampling you do indeed need a column with nominal values. I’m not sure if it is even defined properly on numeric columns.