Message type: E = Error
Message class:  LSOPV - Training Management (Copy of Message Class PV) 
Message number: 749
Message text: Enter a valid reference unit combination
The following combinations of reference units are allowed:
per course
per time unit
per participant
per participant / per time unit
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message LSOPV749, which states "Enter a valid reference unit combination," typically occurs in the context of logistics and inventory management, particularly when dealing with unit of measure (UoM) conversions or when entering data related to stock movements, deliveries, or inventory management.
Cause: Invalid Unit of Measure: The error often arises when the system cannot find a valid combination of reference units (e.g., base unit of measure and alternative units) for the material being processed.
Configuration Issues: There may be issues in the configuration of the material master data, particularly in the units of measure section. Missing Data: The required reference unit combinations may not be defined in the system for the specific material. Data Entry Errors: Users may have entered an incorrect or unsupported unit of measure during transactions.
Solution: Check Material Master Data: Go to the material master (transaction code MM03) and check the units of measure defined for the material in question. Ensure that
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
LSOPV748 Only these values are possible: &
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
LSOPV747 Participation fee will be used since no net amount exists
What causes this issue?  You are attempting to create a credit memo for the invoice amount (net amount). This amount does not exist in old billing doc...
LSOPV750 Unknown error
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
LSOPV751 No course offering is available for the selected course type
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.