Problem solved..thanks..
But 1 more thing, see for my map to build a structure it must be within the range of a road. Thing is, the unit I used for the road is circle of power because I wanted it to be walkable and I changed the model for it to none and made a trigger that whenever such a unit is built the terrain in its position would change to city tile set..what happens is everytime I begin constructing it the construction progress bar won't continue, it stops at 3 hitpoints of its maximum hp and it cannot be targeted. Any solution for this?