Transferring Business Content DataSources IN BW

Now, i'm practicing transfering bc datasource following best practice, but i encount some problems .

1. the system prompt me that "Request TRNK900700 (IDADMIN) belongs to a different client" when i transfer datasource 2LIS_11_VAITM. i never created the request TRNK900700 , which is default ,so i ask why defaut request is TRNK900700 ,and which blongs to a different client, what mechanism behind which(i'm a fresher)?

2. afterward ,i selected another request self-created ,the system prompt me that "2LIS_11_VAITM is locked in request/task TRNK900701", what logical inside it?

in a word ,with articulateness and simpleness, which master could make me understand systematicly request mechaniasm in sap! or offer me some infomation,

thank a lot in advance!