Dear Ram,
In the case where a dump or a SYSFAIL occurs, or some other critical error during the attempted replication, the BDoc would be shown in red. Not all errors coming with R3AD_SAL_ERR cause a sysfail and a red light. For a simple application error which occurs in ERP, the BDoc remains green and the error is returned to the document in CRM.
You can monitor which documents have an error message triggered in the application log in CRM through transaction SLG1.
Best regards,
Julin Xin