I used ambion first choice RLM Race kit but i havent tried to visualize RNA after TAP treatment. Also we have same problems. I couldn't get good band after all. Also I have tried with using Roche 3/5 race kit and still no band. Which taq polymerase do you use? a taq pol with high fidelity may help... Also have you tried 3' race with ambion kit, what about results?

 There might be RNase contamination in your reaction.  Here are some decapping enzymes we developed in the lab that worked perfectly for RACE and other applications: Cat#87 and EZdeCAP (Cat#95).  Please see the attached data sheet for EZdeCAP.

http://www.enzymax.net/mRNA_decapping_enzymes.htm

http://www.enzymax.net/Products/Tobacco%20mRNA%20decapping%20enzyme.pdf

Thanks a lot, we'll have a look at those enzymes.