Noob sql injection question

Ok so this is my first time performing an SQL injection, I found a site that is vulnerable. I did the ORDER BY command to find the number of colums on the page and that came out to be 4. Ok, so then I tried to use the UNION SELECT command to find the names of the tables and i keep receving this error:

Microsoft OLE DB Provider for ODBC Drivers error '80040e14'

[Microsoft][ODBC SQL Server Driver][SQL Server]All queries in an SQL statement containing a UNION operator must have an equal number of expressions in their target lists.

/industry/industry.asp, line 13

I was wondering if anyone would be able to give me a little help on this one. -Thanks

im not really good at this but try

UNION SELECT NULL,NULL,NULL,NULL

again im not good at SQL so this could be wrong but there you go

Thanks for the help man, it was my mistake i had the wrong number of tables.

did it work??