android build not working

I have Unity 3d version 5.3.2. When i initially installed it, i had not downloaded the android build. i did that later. after that in the build settings android module shows but when i click to build the apk a window pops up to select my destination file. now no matter where i put it, the save button doesnot work. i clicked it a thousand times with no response. i clicked and waited for about even 10 mins to see if anything happens. that too dint work. how to proceed here