Catching Text Message From Exception

I can't catch the text message from a exception because ex.getMessage() is null.

Code is
 
try {
        .......
    } catch (Exception ex) {
            System.out.println("Error "+ex.getMessage());
            Logger.getLogger(Soap.class.getName()).log(Level.SEVERE, null, ex);
            statD.errMessage = ex.getMessage();
            statD.succes = false;
            return statD;
        }

And the program writes at the console:
 
Error null

Also on the console screen I can see the following message:

Apr 10, 2014 3:00:38 PM SoapUtils.Soap setPostVarsSEVERE: nulljava.lang.NullPointerException at SoapUtils.Soap.setPostVars(Soap.java:830)
Line 830 of Soap.java is inside the try {}.

Why is the ex.getMesage() null?