Increase AUTO_INCREMENT value in phpMyAdmin
If your auto increment column is of type UNSIGNED SMALLINT, then you'll have the 65535 limit.
Changing the column type to like UNSIGNED INT should allow you up to 4294967295. 
You can use  UNSIGNED BIGINT if you need anything bigger.

If this does not solve your problem, can you post your table structure, which you can get with the statement: show create table &lt;table name&gt;