One possible reason why you are getting the "Grid has dummies" error is that your data has some missing or invalid values that are not recognized by the gridding algorithm. You can try to check your data for any gaps, outliers, or errors and fix them before gridding. You can also try to use a different gridding method, such as Minimum Curvature or Kriging, that can handle missing values better than Bi-Directional gridding.

Another possible reason why you are getting the error is that your grid extents are too large or too small for your data. You can try to adjust your grid extents to match your data range and resolution. You can also use the Draw Extents tool in the Extents and Data tab to interactively draw an outline of the area of interest and create a grid using only the newly specified extents.

A third possible reason why you are getting the error is that your data has a different coordinate system or projection than your grid. You can try to check your data and grid properties and make sure they have the same coordinate system and projection. You can also use the Copy/Convert tool in the Grid and Image menu to convert your data or grid to a different format or coordinate system.