Any of the plug-in functions may encounter an error during processing when using the FM Books Connector. The function will return the string "!!ERROR!!". When an error occurs during processing, immediately call the PCQB_SGetStatus function in order to obtain a full description of the error. This function returns the message associated with the last error. The status is used to identify errors in the request or the processing of requests. The text returned by this function will help troubleshoot script or logic failures and this function call should better help you identify the error.

Please see the “Error Handling” section in the Developer’s Guide found here for proper use of how to trap for errors and call the PCQB_SGetStatus function: 

https://www.productivecomputing.com/documents/FM_Books_Connector/Developers_Guide_FM_Books_Connector.pdf