title: How to call a function in vba which is already assigned to a button
body: <p>I tried to create a ribbon in excel and I was successful. Now I have assigned a macro to a button.</p>
  
  <pre><code>Function delete_cells(control As IRibbonControl)
  </code></pre>
  
  <p>Now, I created another macro, from which I need to call the function <code>delete_cells</code>. I tried to call it as below.</p>
  
  <pre><code>Function modify_cells(control As IRibbonControl)
  delete_cells
  End Sub
  </code></pre>
  
  <p>I am getting an error saying <em>Argument not optional</em>. Please help me with this error.</p>