Donna:

This is not too likely an explanation - but since you said that your Schiff 
reagent was new- I thought that I might put it out for what it is worth.  We 
once got a bottle of Schiff reagent that was intended for use in Chemistry 
for the detection of aldehydes, and it gave a much reduced reaction.  When we 
got the right Schiff reagent, our problem disappeared.

Freida Carson