I have a problem related to solving the complex equation of dispersion relation.

In the plots some modes are missed. I dont know whay?

Is possible to help me? (m0^2<0).

restart;
 with(plots):
 rrr:=proc()
 local ce,c0,ve,va,cte,ct,me,m0,DT,n,EQ,i;
 ce:=6.2;c0:=0.25;ve:=5.25;ck:=1.06;ct:=0.243; cte:=2.515;
 me:=sqrt(((ce^2-v^2)*(ve^2-v^2)/((ce^2+ve^2)*(cte^2-v^2))));
 m0:=sqrt((c0^2-v^2)*(1-v^2)/((c0^2+1)*(ct^2-v^2)));