How to use If with long instructions?

Question

I would like to execute the following code, in which if the condition is true it should execute two instructions instead of one. When I run the code the instructions are executed, but no result is shown.

Ac = Input[];
Print[Ac];

If[Ac == 1,

   instruction1

   var := instruction2;

  ];

the instruction1 should show a grid in which you can modify the value of 4 parameters, and the instruction2 should use the value of these dyanmic variables in order to compute the result.

Instruciton1 is:

Grid[
    {{"", "Theta", "d", "Alpha", "a"},
     {"Link1",
      InputField[Dynamic[Subscript[th, 1]], FieldSize -> 3], 
      InputField[Dynamic[Subscript[d, 1]], FieldSize -> 1], 
      InputField[Dynamic[Subscript[alpha, 1]], FieldSize -> 4], 
      InputField[Dynamic[Subscript[x, 1]], FieldSize -> 1]
      }}, Frame -> Darker[Gray, .6],
    Alignment -> {{Left, {Center}}}
    ]

Isntruction2 is:

linea[Dynamic[Subscript[th, 1]], Dynamic[Subscript[d, 1]], 
    Dynamic[Subscript[alpha, 1]], Dynamic[Subscript[x, 1]]]

Instruction1 and Instruction2 give the following result, cf image.! image

I haven't found any documentation about it. Is it possible to use the If function in Mathematica or should I use another one?