Max Function Isn't Working in SQL Server 2005

Question

I just want to find the max value from the Visitor table. Last is working fine but when digit come VI9999 after that it always returns max value same not VI10000. Please Suggest me what I will do for this...

Thanks in Advance..

Sql query:

select MAX(TSID) 
FROM VISITOR_TABLE;

Answer 1

select Max(cast(substring(TSID, 3, 10) as int)) 
FROM VISITOR_TABLE;