Server was unable to process request. ---> Object reference not set to an instance of an object

   

   

     
         <faultcode>soap:Server</faultcode>         <faultstring>Server was unable to process request. ---> Object reference not set to an instance of an object.</faultstring>         
     

   

   
   

while using SoapUI to call a webservice,you may recieve the message at top 
this was because request xml is not well formed some tags in request xml is not fits to webservice syntax 

for example in request xml 
if needed tag 
but your request xml this block is written as 

will give this kind of error.

So before digging into code firstly check request xml 
even better if you use SoapUI application create a new Request object for your webservice and fill datas in new request clearly..