class version problem

I want to implement java program spcially Packet-capture using jNetDev.jar, For this I download all the nessary files as requied as Follows

1. I installed Wincap 3.1 on Windows xp

2. I m using J2SDK 1.4

3. copy all the necessary files(jNetDev.jar,jNetDev.dll ) in working directory

4. set the appropriate class path

5. When I compile any java program by the following command

javac -classpath jNetDev.jar Capture6.java

Then I get the following error message

Capture6.java:38 : Can not access jNetDev.jND_CaputreSession bad class file :jNetDev.jar(jNetDev/jND_CaputreSession ) class file has wrong version 49.0,should be 48.0

I coudn't understand this problem . I tried many times with other option but I m unable to e compile any java program of the jNetDev[1].10-14-2005.zip

Sir Pls help me . It is a very nessary.I would be grateful if some attention is given to me

[938 byte] By [vivekricha] at [2007-10-3 5:14:53]