public PCAPanel(AlignViewport av, SequenceI[] s) {\r
\r
this.av = av;\r
- if(av.getSelectionGroup().getSize()>3)\r
+ if(av.getSelectionGroup()!=null && av.getSelectionGroup().getSize()>3)\r
{\r
s = new Sequence[av.getSelectionGroup().getSize()];\r
for(int i=0; i<s.length; i++)\r