This issue may occur when you have read-write permission, but don't have ddl_admin permission.

Get execute permission from your DBA to execute procedure.

Command:

Grant Execute to [userName];

Ref.

http://stackoverflow.com/questions/9321334/grant-execute-to-all-stored-procedures

Check below solution. No need to write extra lengthy code.

http://bidn.com/blogs/DustinRyan/ssis/915/check-isnumeric-with-derived-column-transform-in-ssis-package

May be this is scale & not precision as per below query.

Select * From sys.types D Where D.name Like '%date%'