i am getting compile error

javac DocReader.java
DocReader.java: 4: package org.apache.poi. hwpf does not exist
import org.apache.poi. hwpf.HWPFDocume nt;
^
DocReader.java: 5: package org.apache.poi. hwpf.extractor does not exist
import org.apache.poi. hwpf.extractor. WordExtractor;

i have already added the poi-3.0-alpha2.jar and also set the path in the command prompt....