can't harvest flax

[dakepwns]

I have some flax plants that are fully grown (all flowers are blue). I have the farming skill and have successfully harvested beetroots already. When I click harvest on the flax, nothing happens.

[DDDsDD999]

They're not ready.

[Long-Gone]

There are stages to the growing, each with different sprite images. They go blue in the second stage/third stage.. but it is only when they are tall and blue that you can harvest them.