First, you really should say what is "wrong" with the graph, or better post it.
Second better is to provide actual data.
Below are a couple of data steps that create what I an guessing is your problem, a few values that are relatively much large larger than the values that would comprise the box part of the plot and a default plot. Then follow two approaches to controlling the Yaxis to display some box.
Data and default plot:
data plot2;
do i=1 to 100;
x=rand('normal',5.0e-8,1.0e-8);
output;
end;
/*add a few larger values*/
do i=101 to 110;
x=rand('normal',3.0e-4,1.0e-4);
output;
end;
run;
PROC SGPLOT DATA= plot2;
vbox x;
run;
And two different plots:
/* force yaxis to show smaller range trims outliers*/
PROC SGPLOT DATA= plot2;
vbox x/;
yaxis values=(1.0e-8 to 1.0e-7 by 5.0e-9);
run;
/* use log axis*/
PROC SGPLOT DATA= plot2;
vbox x/;
yaxis type=log logbase=10 logstyle=linear;
run;
The actual range of values and increment in the VALUES= option likely need tweaking for your data.
It may also help to increase the size of your graph display area with an ODS Graphics option statement.