OK, let's test it:
Please open a terminal and type "which amuleweb". It will either give you the path to amuleweb or tell you there's "No amuleweb in (...)"
In the latter case, please open the Synaptic package manager and make sure the amule-daemon package is installed. In the first case, please check aMule's log file in the hidden directory ".aMule" in your home directory for any error messages and tell us what it says.