I have been modelling a mould in gambit. But i'm not able to connect the points 20e-6 and 30e-6. The error says the edge degenrates into a point. Can anyone help me about it?

Your points too close for the Gambit tolerances. Try working in smaller units and re-scaling your mesh inside fluent.

I have had the same problem. Even if you can get the points far enough apart for Gambit to recognize them, when it goes to mesh the geometry, it won't come out nice. Since you can set the units in Fluent, make everything at 1m scale, and define a new length unit with a conversion factor of 1e-6