I'd like to see a reference for tis reaction. I don't think you can form his wih NaOH.
Why not? Which step? The aldol step or the condensation step?
I can't think of any objection one could have with the aldol step.
The condensation product is wrong though. The base will pull a proton from the most acidic (next to the carbonyl group, in this case there's only one such carbon ) source, leading to enolization, double bond migration, and loss of hydroxyl group to produce an alpha-beta unsaturated aldehyde.