An expression of non-boolean type specified in a context where a condition is expected, near ','

I am getting the error message, "An expression of non-boolean type specified in a context where a condition is expected, near ',' " when running an ssrs 2008 r2 report.
The sql embedded in the dataset is:
IF @reportID <> 0
BEGIN
  SELECT 'Students report 1' AS selectRptName, 1 AS rptNumValue
  UNION
  SELECT 'Students report 2', 2 
  UNION
  SELECT 'Students report 3', 3
  UNION
  SELECT 'Students report 4', 4
  UNION
  SELECT 'Students report 5', 5
  ORDER BY selectRptName
END
)

The sql runs fine in managment studio when I declare @reportID.

The sql runs fine with I comment out  'IF @reportID <> 0'.

The @reportID is a parmeter value that is passed to the applicable dataset.
The @reportID can have more than one value.

Thus can you show me sql and/or tell me what I need to do to solve the issue for me?