sharepoint - CAML Query SPException -

i'm trying execute caml query, have spexception every time.

here query :

<where>      <and>         <eq>              <fieldref name='user' />                  <value type='computed'>                      " + foo + "                  </value>         </eq>         <and>             <eq>                 <fieldref name='title' />                     <value type='computed'>                         " + bar + "                     </value>             </eq>             <eq>                 <fieldref name='month' />                     <value type='computed'>                         " + xyz + "                     </value>             </eq>         </and>     </and> </where> 

here use.

var query = new spquery                     {                         query =                             @"<where><and><eq><fieldref name='user' /><value type='computed'>" + foo +                             "</value></eq><and><eq><fieldref name='title' /><value type='computed'>" +                             bar + "</value></eq><eq><fieldref name='month' /><value type='computed'>" +                             xyz + "</value></eq></and></and></where>",                         viewattributes = "scope=\"recursiveall\""                     };                      result = listtoquery.getitems(query); 

every properties of splistitemcollection result threw exception of type 'microsoft.sharepoint.spexception'.

i checked columns internal names, seems alright. query i'm trying if(user == foo && title == bar && month == xyz). query parameters strings.

did miss in query ?