Aruna,
Oh yeah.. i got it here in the specification too.
beanName="{package.class | <%= expression %>}" type="package.class"
Instantiates a Bean from either a class or a serialized template, using the java.beans.Beans.instantiate method, and gives the Bean the type specified in type. The Beans.instantiate method checks whether a name represents a class or a serialized template. If the Bean is serialized, Beans.instantiate reads the serialized form (with a name like package.class.ser) using a class loader. For more information, see the JavaBeans API Specification.
So it should work with "package.class.ser" , in your case it is my.Mybean.ser. try this.