Overlap PCR that will notamplify - (Jul/19/2001 )

Maybe you should follow a method for overlap PCR that is described in YEAST, 12, 259-265, 1996 by Wach, A.

This method has worked for me!

I have two PCR products of ~250bp and 200bp which have a region of complementary sequence. When I try the overlap PCR I get a Band of 850bp but when I try to add primers to amplify the 850bp band it will not work I do not know if the primer binding sites are present but I have the correct 850bp band and I have tried the two primers in standard PCR reactions using a plasmid as a template and both work. I do not know what else to do.All my PCR components work in other PCR reaction but just not the overlap.