We can see below error in SOAP Request/Reply palette when we send SOAP request using SOAP over JMS.

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An IO error while trying send soap message [ An IO error while trying send soap message [ com.tibco.spin.transport.JMSIOException: There was an unexpected error while sending a message. ] ] at com.tibco.plugin.share.soap.errors.DefaultSoapErrorHandler.throwEngineException(Unknown Source)
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Cause : The issue occurs if the EMS side did not have the correct permission for the application used to access the queue.

While sending soap request using SOAP over JMS the "An IO error while trying to send soap message" error occurs.

Check the EMS log, if there is an error related to queue permission then set the correct permission and restart the designer.