Error: SQLSCRIPT: identifier must be declared: _total_ucnt

  I am calling dynamic select statement using  EXECUTE IMMEDIATE( :lv_query); in AMDP method. But i am getting sytax error like SQLSCRIPT: identifier must be declared: _total_ucnt.

   i do not use this variable in my AMDP method and error is resolved when i commented the statement EXECUTE IMMEDIATE( :lv_query);

can anybody please help on this? and is it possible to get back result of select query is executed using EXECUTE IMMEDIATE statement.