RFC channle used in UDF is running with No Name space error

Hi,

We have migration PO 7.4 to 7.5 version and all UDF which is used RFC lookup channel are not working and all are failing with below error.

Error in processing caused by: com.sap.aii.adapter.rfc.afcommunication.RfcAFWException: error while processing message to remote system:com.sap.aii.adapter.rfc.core.client.RfcClientException: could not get functionname from XML requst: com.sap.aii.adapter.rfc.RfcAdapterException: failed to read funtionname from XML document: missing namespace declaration(2)

We trying by replacing RFC look up but its was used in some other fields inputs.

Please share some inputs have to over come from this issue.

Regads,

Naga Uday.