I need to display a line chart from years 96, 97, 98, 99...
The cube I'm using has only year 97 and necessary measure and data item..
Can I use the other years from different cube?
Short Answer: No
Long answer: You'd have to create a new FM model with 2 cube data sources in it to create a single package with 2 cube data sources.
http://publib.boulder.ibm.com/infocenter/cbi/v10r1m1/index.jsp?topic=%2Fcom.ibm.swg.ba.cognos.ug_fm.10.1.1.doc%2Fc_workingwithdatasourceconnections.html
check this
http://www.ibm.com/developerworks/data/library/cognos/reporting/dimensional_queries/page495.html