We are in S4 platform however the feature may also be available in R3.
We have defined a custom tab layout for the Appropriation Request Master data as it as custom tabs and custom fields inside it. When we open IMA11 transaction in the Worklist Mode On then its fine. However while selecting work list mode off in IMA11 system gives a message :
App. req. does not use standard layout - display by work list only
Message no. AO199
The same obviously works when I use a standard layout but here we have not configured so as there are custom fields.