I think the reason for this error may be because the object that you are dealing with will be locally stored.
Either Use the transaction SE03 to change its directory to make it a transportable object and then try adding it to a Request. Or else while moving the same to a package other thank $TMP, It will ask for request and select your requset and the R3TR- TABL entry will fall in your request.
For this,
Goto -> SE03, Select Change Object Directory Entry,
Provide Your table name against -> R3TR- TABL Entry,
Execute it
Docuble clik on the packge(Here $TMP)
Select appropriate package
Select appropriate Request
Save