Cannot drag anything onto the workspace

Hi guys,

I'm working with Visual Composer under Composite Environment 7.1 SP3. I canno drag anything onto the canvas...

information from the console:

Ready

[E] Failed to layout shape(s): 'elmBoard.boardObj' is null or not an object

[E] Failed to layout Unit: 'elmBoard.boardObj' is null or not an object

[E] Failed to send signal to the board : 'elmBoard.boardObj.onsignal' is null or not an object

[E] Failed to send signal to the board : 'elmBoard.boardObj.onsignal' is null or not an object

Thanks in advance 😊

Wenhao