Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_21795 ( "Poll Source" text, "Dates administered" text, "Democrat: Jay Nixon" text, "Republican: Kenny Hulshof" text, "Lead Margin" text )

### Question ###
How many different lead margins were stated in the poll administered on September 11, 2008?

### Accurate SQL ###

SELECT COUNT("Lead Margin") FROM table_21795 WHERE "Dates administered" = 'September 11, 2008'