I am trying to use Ctrl+ws to split a window in vim. However it is not working in my case. I opened a file using vim filename. Then I pressed Ctrl+ws. But as soon as I press just Ctrl+w it clears the viewport and I could see my shell display before vim opened the file. I mean the view port is replaced by the content just before the file was opened. However, I am still editing the file with vim.

Suggestions?