when opening the bouncingballwithimport file which i have downloaded is showing this error

[1] 12:49:54 Translation Error

[bouncingBallWithImport: 3:3-3:68]: Class Modelica.SIunits.Length not found in scope bouncingBallWithImport.

[2] 12:49:54 Translation Error

[bouncingBallWithImport: 4:3-4:45]: Class Modelica.SIunits.Length not found in scope bouncingBallWithImport.

[3] 12:49:54 Translation Error

[bouncingBallWithImport: 5:3-5:49]: Class Modelica.SIunits.Velocity not found in scope bouncingBallWithImport.

[4] 12:49:54 Translation Error

[bouncingBallWithImport: 6:3-6:82]: Class Modelica.SIunits.Acceleration not found in scope bouncingBallWithImport.