include files from other extension

[typo27]

Hello,
I am developing an extension and want to include file from other extension:

require_once(t3lib_extMgm::extPath('other_extensio n').'other_file.php');

Unfortunatelly, that doesn't work on customer's server, while on my does.

What can be a problem here?

Sposibo

[void]

Is that extension which you rely on installed on the customer's server?
I never had such probs. Maybe you need to add dependencies in your ext_emconf.php