abstraction for buggy file error

Hi!
When I use your model,I encountered the following problem
”
Could not find CtElement at line 3 in /roor/chai/src/buggy_file.txt
Cannot generate abstraction for buggy file
“
and the buggy_file.txt is shown below
"
public class InvalidMatrixExceptionTest extends TestCase {
public void testConstructorMessage ( ) {
String msg = "message" ;
InvalidMatrixException ex = new InvalidMatrixException ( msg , new Object [ 0 ] ) ;
assertEquals ( msg , ex . getMessage ( ) ) ;
} }
"
Could you tell me the reason for the problem?