Pls help urgent doubt in sql*plus for my exam?

i installed otacle 9i... th sql version is 9.0.1.0.1... when i try to create a table with the command CREATE TABLE STUDENT(rollno num(5),name varchar2(20), age number(3), total number(5)); i get an error "Nothing in SQL buffer to run". but this command worked out well when i tried in my college computer lab with same version... pls help how to solve the error.