Namespace prefix "oraext" qualifying cannot be resolved while Designing BPEL processes in Oracle SOA Suite 11g

SOA Developers mainly encounters this issue while using Oracle Extension functions in the Assign or Transform activities.

This error occurs when namespace is not defined in your BPEL process. check two points here.
1. Is namespace : http://www.oracle.com/XSL/Transform/java/oracle.tip.pc.services.functions.ExtFunc is already defined in BPEL process or not ? if not, Define it as below.
xmlns:oraext="http://www.oracle.com/XSL/Transform/java/oracle.tip.pc.services.functions.ExtFunc"

2. If namespace is already defined in the BPEL process then you need verify the prefix value here.for example below is the entry found in BPEL process.
 xmlns:ns4="http://www.oracle.com/XSL/Transform/java/oracle.tip.pc.services.functions.ExtFunc"

here you need rename the prefix values "ns4" to "oraext".  OR

modify the function name prefix in Transformation with "ns4"