Shift & not set up for grouping &

What causes this issue?

You entered a shift sequence or shift definition which is not in the
active group or is not valid during the period you entered.
Shift sequences are combined into shift groupings in Customizing. The
groupings for the Logistics area are numbered from 51 to 99. You can
maintain the active grouping for your work center in the header data
for the capacity.
You can also assign new shift sequences or shift definitions to a shift
grouping in the capacity planning menu.

How to fix this error?

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

Select a shift sequence or a shift definition contained in the active
grouping or
change the grouping in the header data for the capacity or
assign a new shift sequence or a new shift definition to the active
grouping. To do this in the capacity planning menu, select the menu
options <LS>Available capacity -> Shift sequence</> or
contact your system administrator to set up new groupings in
Customizing.
<DS:SIMG.SIMG_CFMENUOLPSOP4A>Set up shift grouping</>

Error message extract from SAP system. Copyright SAP SE.