Unable to generate Structured text using PLC coder

Hello all,

I created a simple system for which I want to generate a Structured Text code in PC WORX: a software by Phoenix Contact. Now the supported version in Simulink is PCWORX 6.0. And I have a 6.30.767. I followed the procedure as given in http://cn.mathworks.com/help/pdf_doc/plccoder/plc_st.pdf. However I still get the error Generate and import code for Subsystem failed. I have attached a simulink file of the system I created. It is essentially a replica of the system shown in the user guide.

Request your support and timely help.

Thank you.

Regards, Srikrishnan