java - Eclipse : Cannot generate a serial version ID -

i have issue eclipse 3.6 (helios) :

anytime want generate serial version id (serialversionuid) class extends serializable class, following message :

the following error occured : not find class file. make sure file compilable.

what doing wrong ?

thank you.

in case, i've solved problem following way:

right click project, "build path" -> "configure build path" -> "source" tab, remove paths tagged "missing".