Diggestion Problems!

[amherrera at CIGB.EDU.CU]

 Hi netters!
    I am trying to cut a plasmid first with Kpn I and with EcoR V in a 
    second step.
    The vector linearized well after Kpn I. After these all following 
    steps (1:1 phenol+cloroform, 2-butanol, 0.5 vol NH4Ac 0.6 vol 
    isopropanol, ethanol 70%), I proceed cutting with EcoRV and 
    the vector did not give the expected band.

   Surprisingly the same vector is diggested with EcoRV if I start 
with this enzyme first.This never happpened to me before.

Where's the problem?

    DiogenesQV