Problem with scripts

Hi

my script get error because of defining variables… for example when I use Int_t or Double_t and… for defining variables they are not defined for Root and script does not run. In scripts we must use int, double, float or Int_t , Double_t, Float_t?
How I can fix this problem?

What does it mean “my script get error”?
Show a minimal example of a script for which you get an error in ROOT.