small problem with BASH_SOURCE and PATH

[Alex fxmbsw7 Ratchev]

so i have a project
resulting code contains PATH=$PATH:${BASH_SOURCE%/*}/bin

so i have

./
./script
./bin/
./bin/an.gawk

( small example )
when i run the script like ./script it works
if i run it via 'bash script' it says the gawk not found

any help ? =))