Message type: E = Error
Message class:  VI - Sales Document Indices 
Message number: 106
Message text: Sched.line cat. & of document & and item & not defined in TVEP
Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.
To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.
Unfortunately, there isn't any extra information in this error notice.
First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).
Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.
You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.
The SAP error message VI106 indicates that there is an issue with the scheduling line category for a specific document and item. This error typically arises in the context of sales and distribution (SD) when the system cannot find a valid scheduling line category in the configuration table TVEP.
Cause: The error occurs due to one of the following reasons: Missing Configuration: The scheduling line category for the specified document type and item category is not defined in the TVEP table. Incorrect Document Type or Item Category: The document type or item category being used does not have a corresponding scheduling line category defined. Customizations: If there have been recent changes or customizations in the system, it may have led to the scheduling line category being deleted or not properly configured.
Solution: To resolve the VI106 error, follow these steps: Check TVEP Configuration: Go to transaction code SPRO to access the SAP Customizing Implementation Guide. Navigate to Sales and Distribution
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
VI105 Item category & in document & and item & is not contained in TVAP
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
VI102 Error in SAPLV05I program during delivery date determination (document &)
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
VI108 Order type & from document & not contained in Table TVAK
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
VI109 The units of measure between & and & are not defined
How to fix this error?  Maintain the units of measurement in Customizing (IMG) under 'Global Settings'.Error message extract from SAP system...
Click on this link to search all SAP messages.