why lost data when get from plist file

Question

I have

NSMutableArray *arrTest = [[NSMutableArray arrayWithObjects:@"value 1",@"value 2",
                            @"value 3",@"value 4",nil] retain];

• I stored my array to plist file (ex: sample.plist).-> ok
• I call a method to get that arrTest from above plist file -> ok.
• i use that arrTest to display data in UITableView.
  • but arrTest is error. And i can not get data from arrTest. So to get data in arrTest, i must re-call get data from plist file.

Do you know the reason and how to fix it?

Thank you.