Unable to get messages from Message resources file for keys

We have a web app having 3 layers - Action classes, Service or Business Objects and DAOs.
BOs and DAOs are accessed thru interfaces.
We use spring to inject dependency.

We have defined scope="session" for beans corresponding to actions.
For BOs and DAOs , no scope is defined. We are using applicationContext xml files to define beans.

Labels and buttons names are picked up from MessageResources.properties file.
But on some pages these values are not picked up and labels go missing.

I am new to both Spring and Struts 2 and I am unable to figure that why this is happening.
Message resources are loaded in context and it should be available to all.

Please help me resolve this issue.

Thanks in advance,

Rajiv