in situ with short probes

[JIA at CUCCFA.CCC.COLUMBIA.EDU]

I am currently doing in situ hybridization with DIG-labeled RNA probes 
of 200-300 bp length.  The problem is the sensitivity is very low.
Does anyone has a good protocol or experience dealing with DIG-labeled
RNA probes of short length or just oligos?  Your help will be greatly 
appreciated.
R. Jia, Columbia U.