I have a db in oracle(named pcadb).in application layer i work in jdeveloper 10g.in jdeveloper i make a new business component project (named pca_module3), connect it to pcadb and make entity object and view object for any table of pcadb .link and association made automatically.i design my forms and reports in another project(named pca view) that use pca_module3 .but when i run pca view i have some error like this :

Error: pca_module3.TActivity: Entity pca_module3.TActivity requires a primary key. Please select the attribute(s) that identify an instance of the entity.

for some table like Activity it doesn't know attributes(columns) it mean that when i right click on TActivity entity object for editing,the columns of Activity table don't show in attribute part.????!!!!

i have 25 tables but this error is just about 9 tables .

do you khnow what shall i do?