Error in Surface mesh of region Region 1: No triangles in surface

This error was found when I import geometry in an exixtin star ccm+ template, which i have created by deleteng the geometry portion from a completed model.
When I Open 'Import' under Representations, Number of faces was showing as 0 in properties.
I have solved this by performing following step.
1. deleting everything except geometry under Representations (i.e. Initial Surface and Import)
2. Initialize meshing (initial surface will be created again while you do this))
3. mesh

AMG coarsening halted - Star CCM+

While running a CFD, i got this error at 10th iteration

WARNING: Ap = 0 on multigrid level X, nRows = XX, blockSize = X
         AMG coarsening halted.

This is due to small un conected surfaces in mesh
To rectify this right click and select repair surface in Representation >> remeshed surface, which you can find below plots

A new window called Surface Prepration Options will pop up. Click OK

In the side pane, select mode as "Edit conected surfaces" from the drop down and click start diagonosis

it will display more than one line of surface groups in a table.
Highlight and delete the small unconnected surfaces and close the window.

Select generate volume mesh to remesh