title: excel2img gives error "Exception: Failed locating range rez-2!A1:A3"
body: <p>if my sheet contains <code>-</code> symbol - its raise error, but when i rename it to <code>rez2</code> - all works</p>
  
  <pre><code>export_img("test2.xlsx", "rez.png", "rez-2","rez-2!A1:A3") #"Exception: Failed locating range rez-2!A1:A3"
  </code></pre>
  
  <p>Problem with this code in lib</p>
  
  <pre><code>rng = excel.workbook.Application.Range(_range)
  </code></pre>