There's no problem with relative URL. In this case, the problem is that it contains a space, which is not a legal character in a URL. Try:
Better still, rename the JAR as "smartfacedemo.jar", and change the JAD to match... avoid "unusual" characters file names (anything other than a-z, 0-9 and "_"), and ideally don't mix upper and lower case (as you get different behaviour between case-sensitive and -insensitive file systems, either on the device or the deployment server).
(I say no problem with relative URLs... I think some Sagem devices need an absolute URL.)