Since starting to play the first time FIFA 07, there is a problem for which I couldn't find any solution on these (or other) forums: during gameplay, while deciding to manage my own team (for instance making a substitution), I am unable to use the "team management" button, as well as some of the other related buttons in the pause menu - the message which appears is "you have to assign a controller to one of the teams in order to make a substitution" (or something close to that).
The idea is that I already assigned a controller (keyboard), and although browsing through the "control" options of the game in order to find a solution I couldn't find any clue about what should I do.
Does anybody have an idea about this?

Two theories. Firstly, the game does not (always) seem to consider the mouse to be the same control mechanism as the keyboard, so you need to select Team Management using the keyboard rather than the mouse. Secondly, there seem to be situations where I see this purely using a gamepad, but in all cases it has been during 'cut scene' play elements (eg. kick offs before you get control) when just letting the game run for a few more seconds resolves the problem.

Thanks, Steve, for the quick reply, that did it! Using only the keyboard is the solution. Enjoy the game!