(1) Insert four employees into three leaders, first in a straight line, but the first one cannot be the leader at the same time (in that case, the leaders will be adjacent after circling). When there are three gaps, the last employee has three choices and seven rows.

(2) All four employees are arranged in ***24 rows.

(3) The three leaders are all arranged in six ways.

To sum up, there are 24× 6× 7 = 1008 arrangements.

I just did this problem. Ha ha.