Hi Isushant,
OK, so it's not the problem with the imported WSDL file.
I'm falling back to my original suspicion - the fault is probably on the server side.
It is the server reporting the fault I'm assuming something is wrong with how it processes the incoming SOAP request that was assembled by soapUI. You may want to start by checking how request arguments (apiNames, zone, xml, returnFormat) are handled by the server since these arguments can be anything (i.e. they're of xsd:anyType type)
I hope you'll be able to find the root cause of this fault.
Cheers!
/Nenad Nikolic a.k.a. Shonzilla