Wrapping OpenSCAD code in module breaks code -

my problem simple: have code renders want, when put module, openscad throws error when render saying no top level object found.

    difference()     {         flipper(length, res, chord, xlambda, xa, ylambda, ya, phase);         //dye channels         dye_channel(len_dye_1, loc_dye_1, chord, xlambda, xa, ylambda, dye_r_1);         dye_channel(len_dye_2, loc_dye_2, chord, xlambda, xa, ylambda, dye_r_2);         //dye_outlet         translate([0,0,len_dye_1*floor(xlambda*chord)]) rotate([0,90,0]) cylinder(r=dye_r_1,h=loc_dye_1,$fn=25);         translate([0,0,len_dye_2*floor(xlambda*chord)]) rotate([0,90,0]) cylinder(r=dye_r_2,h=loc_dye_2,$fn=25);         //screw holes         translate([loc_screw_1,0,0]) cylinder(r=screw_r_1,h=len_screw_1);         translate([loc_screw_2,0,0]) cylinder(r=screw_r_2,h=len_screw_2);     } 

when put module, error.

    module dye_flipper(len_dye_1, len_dye_2, loc_dye_1, loc_dye_2, len_screw_1, dye_r_1,     dye_r_2, len_screw_2, loc_screw_1, loc_screw_2, screw_r_1, screw_r_2, length, res,      chord, xlambda, xa, ylambda, ya, phase)     {...} 

the functions of other routines little complicated, , imagine treat them black box. difference code produces object want. put module because seems programming practice me.

sounds simple… calling module after defining it? dye_flipper(…)