command line problem

Dear list,

maybe a silly question from a non-unix user working with OS X:

Here is my ImageJ directory:

ZMKKFO:~ stammt$ cd /Users/stammt/Desktop/ImageJ

Using:
java -jar ImageJ.app/Contents/Resources/Java/ij.jar
everything works well.

If I want to avoid the cd and type the extended path:
java -jar
/Users/stammt/Desktop/ImageJ/ImageJ.app/Contents/Resources/Java/ij.jar

then ImageJ alerts:
Plugins folder not found at /Users/stammt/plugins/

How can I solve this problen?

Many thanks in advance

Thomas