[gentoo-user] Checking the reason for (-useflags) in brackets

Hi,

for some applications I want to activate some USE flags, which are
disabled by default.

Some of those USE flags are set in () brackets. From searching the
internet I learned, that this may be due to unresolveable dependencies
or settings in the make.profile or....

Is there a way to exactly pin point the reason why a certain USE flags
gets "(diabled)" and whether it is possible to resolve the problem?

How can I figure out that?

Thank you very much in advance for any help!
Best regards,
mcc