[Luca Dimonte]

Here

if(strcmp(cmdtext, "/InviteDrift", true) == 0)
{

tmp = strtok(cmdtext, idx);

you are comparing the whole thing typed by the player (maybe "/invitedrift 5"?), so that's different from "/Invitedrift", and will never find the command.

Later you store in tmp the playerid.

tmp = strtok(cmdtext, idx);

If you see that, you forgot to do the same in the if statement. It would be

tmp = strtok (cmdtext, idx); // added
if(strcmp(tmp, "/InviteDrift", true) == 0)
{
tmp = strtok(cmdtext, idx);