Link could not be carried out -> see message log

What causes this issue?

The link you require could not be carried out by because the system
found a contravention of the consistency rules.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Analyze the message log (accessed by choosing Goto -> Message log).
This log contains more detailed information as to which consistency
rules were broken.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.