If $a \in R$ and the equation $- 3 ( x - [ x ] ) ^ { 2 } + 2 ( x - [ x ] ) + a ^ { 2 } = 0$ (where $[ x ]$ denotes the greatest integer $\leq x )$ has no integral solution, then all possible values of $a$ lie in the interval\\
(1) $( - 2 , - 1 )$\\
(2) $( - \infty , - 2 ) \cup ( 2 , \infty )$\\
(3) $( - 1,0 ) \cup ( 0,1 )$\\
(4) $( 1,2 )$