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_3155 ( "Tie no" real, "Home team" text, "Score 1" text, "Away team" text, "Attendance" real, "Date" text )

### Question ###
When the away team is Millwall, what is the total possible amount of tie numbers?

### Accurate SQL ###

SELECT COUNT("Tie no") FROM table_3155 WHERE "Away team" = 'Millwall'