new fish and tank divider

[rockstar26]

i just went over to the new 10 gallon tank i bought, i split it down the middle with a tank divider....

WELLLLLLLLLLLLLLLLLL

i put my new fish spook on one side of it, went back about a half hour later and BAM he was on the other side of the tank!!....

i had it secured on the bottom with the gravel, and the water level is about an inch lower then where the top of the divider is....

my guess is he got through where the edges are supposed to go securely against the outter edges of the tank............. how do i fix this?