The type 'x' in 'x.cs' conflicts with the imported type 'x'
<p>What is causing this build error?</p>

<p>The type '<em>AriaLibrary.AriaBL.Book</em>' in </p>

<blockquote>
  <p>'I:\Programing\MyProgram\Library\AriaNetDelijanCorporation\AriaLibrary\AriaBL\AriaBL.cs'</p>
</blockquote>

<p><em>conflicts with the imported type</em></p>

<blockquote>
  <p>'AriaLibrary.AriaBL.Book' in</p>
  
  <p>'i:\Programing\MyProgram\Library\AriaNetDelijanCorporation\AriaLibrary\bin\Debug\AriaLibrary.exe'.</p>
  
  <p>Using the type defined in
  'I:\Programing\MyProgram\Library\AriaNetDelijanCorporation\AriaLibrary\AriaBL\AriaBL.cs'.</p>
  
  <p>I:\Programing\MyProgram\Library\AriaNetDelijanCorporation\AriaLibrary\UI\Document\Book\frm_AddNewBookISO.cs   24  16  AriaLibrary</p>
</blockquote>
