Im late on the Party, but: on mobiles you have to choose whether you want to use GLES1, 2 or 3 on create of your "window", then you are tied to that version. GLBasic creates its surfaces with GLES1, simply because all drawing commands are written on old, depreciated GL. That means you cant use shaders at all.
You would need to close GLBasic's, window and create a new one, with GLES2 enabled. Even if it works, it will have huge side effects, like GLBasic drawing commands wont work at all, some others probably too... So no easy task, as long as the GLBasic core does not get rewritten (which would be a huge pile of work).