OPC UA client certificate issue

I have created opcua certificate for my webclient to communicate to the opc ua server in the ctrlX CORE. i can establish the connection without any issue but sometime i am getting this kind of error msg :

client_secure_channel_layer   :236   requestData not found for requestId =  84 try with  85 
Error writing data: Invalid message header detected
Error writing data: Invalid message header detected

Writing data: ns=2;s=plc/app/Application/
Error writing data: Invalid Channel BadConnectionClosed
Error writing data: Invalid Channel BadConnectionClosed

and i think because of that write operation is not successful. 

do I have to create proper certificate for reliable communication? I need help in this regard.

I can not attach certificate here because of unsupported datatype.

Thank you!!