By my meance you use too little vector for such large fragment. May be you
could use cosmid or lambda phage...
See Sambrook, Maniatis and Freech (it may be mistakely writing) manual.
>I´ve tried to ligate a 6kb-fragment into a Gal4-Transformation-Vektor
>(p221-4; 12kb long), but failed several times. Does anybody have a
>protocol or reference for such a cloning problem ?? I hope, it´s not
>impossible
