CALL_FUNCTION_NOT_FOUND ABAP Run Time Error

I realized CALL_FUNCTION_NOT_FOUND ABAP Run Time Error in ST22 transaction screen in the list of runtime errors. The function module called in the ABAP code belongs to a SAP Smartform output document. I was able to figure the print program in Terminated Program column of ST22 transaction screen showing where the CALL_FUNCTION_NOT_FOUND runtime error occurred.

CALL_FUNCTION_NOT_FOUND ABAP run time error in list of SAP ST22 transaction list

In ST22 transaction screen where run time errors are listed, go details of the CALL_FUNCTION_NOT_FOUND ABAP error. You will be directed to Runtime Error Long Text screen where there is very detailed information about the ABAP error occurred on SAP system. If you go to Source Code Extract, you will see the ABAP code lines which caused the error.
The error happened at "CALL FUNCTION ssf_name" line where the SAP Smartform function module is called by a function call within the print program.

After detecting the Smartform name, I used Smartforms transaction to display the target output document. Then I generate the form using the top menu options Smart Forms > Generate (Ctrl+F3) and then executed Test F8 to see if the function module is created successfully. After you are sure that the Smartform output document is activated successfully and the function module is generated without error, the reason for the CALL_FUNCTION_NOT_FOUND ABAP run time error will dissapear.

You can test your output with a sample document number and see whether the runtime error still exists or not.