running testNG xml via cmd prompt

my test NG jar is in C:\TestNG\testng.jar,' testNG xml : D:\auto\auto\testng.xml java classes: D:\auto\auto\src\CloudPlatform\*

selenium: ;C:\Users\muthus\Downloads\selenium-java-2.43.1\selenium-2.43.1\selenium-2.43.1.jar

Ive set classpath as : C:\TestNG\testng-5.5.jar;C:\Users\muthus\Downloads\selenium-java-2.43.1\selenium-2.43.1\selenium-2.43.1.jar;D:\auto\auto\src\CloudPlatform\*

Am unable to run it via cmd prompt with the below issue:

D:\auto\auto>java -cp C:\TestNG\testng-5.5.jar;D:\auto\auto\src\CloudPlatform\*; 
org.testng.TestNG testng.xml

Error:

D:\auto\auto>java -cp C:\TestNG\testng-5.5.jar;D:\auto\auto\src\CloudPlatform\*;
 org.testng.TestNG testng.xml
Exception in thread "main" org.testng.TestNGException:
No sourcedir was specified
        at org.testng.TestNG.checkConditions(TestNG.java:1170)
        at org.testng.TestNG.privateMain(TestNG.java:1010)
        at org.testng.TestNG.main(TestNG.java:997)

Need your valuable help on this!