I couldn't find another note than the one Duke already mentioned.
Did you read that?
"One workaround for this problem is to define the entire expression as a
macro earlier in your job definition, then invoke this macro in the
Expression Builder window."
Not that this is pretty but: You could assign the whole expression to a macro var in the pre-processing part of your job and then just call this macro var in the expression builder window (I think that's under advanced where you can write your own expression - click, click...)
You have always the possibility to open a support track with our friends from SAS Tech Support:
http://support.sas.com/ctx/supportform/index.jsp
HTH
Patrick