Almost everytime I have made a cake I have had a problem with the filling oozing out when I put the top layer of the cake on. I know to pipe a dam of icing then put your filling in then top with cake but everytime the filling over flows the dam or the dam spills out the side and I end up haveing to take it all off and try again, any tips please!
Crystal

How much filling are you using?

Here's a sleeved pastry filling usage chart by cake sizes:
(So you can compare how much they recommend and you actually used.)

http://www.countrykitchensa.com/ckideas/ckidea.aspx?Occ1Id=&ideaId=168&idea=494&occasion=General%20Cake%20Instructions

leah_s "trick" may also work for you:

http://cakecentral.com/cake-decorating-ftopict-633571-.html

HTH