Anyone successfully doing RNAse protection Assays?

[genes at unixg.ubc.ca]

I have started doing RNAse protection assays using an Ambion kit(RNAse 
II). I can't seem to get it to work. The probe is 600 bp and is made 
from a pGEM plasmid containing an insert. The target is made from a 
longer sequence that is in another plasmid (probe was actually 
subcloned from this longer sequnce). I am trying to titre the reaction 
so as not to use up my total RNA sample that is limited. The control 
for the kit works fine. Can anyone give me some pointers on making the 
probe or the target sample and getting this to work. 
Any help will be greatly appreciated.
Craig