Below is some of the common deployment problems and solutions.
https://www.ibm.com/support/knowledgecenter/SSAW57_8.0.0/com.ibm.websphere.nd.doc/info/ae/ae/rtrb_installappprob.html
If this doesn't help, you can enable the deployment trace to find out the root cause exception.
http://www-01.ibm.com/support/docview.wss?uid=swg21199344
Hope it helps...
Eric