VDMA configuration in Python on Pynq-Z2

I am trying to configure the VDMA in Python on Jupyter Notebook with the following design but something is wrong because the connection with the board is being lost after i run the last lines…
How can i configure VDMA?

I follow the instructions from:

I also used the following code in Python but when i run the last code “vdma.writechannel.start()” my monitor is still blank but it shows “inappropriate format” instead of “no signal”.