public OnPlayerCommandText(playerid, cmdtext[])
{
    enum VarsEnum
	{
	    cmd[256],
	    tmp[256],
	    tmp2[256],
	    pname[MAX_PLAYER_NAME],
	    idx

	}
	new Vars[VarsEnum];
	Vars[pname] = PlayerName(playerid);
	
	set(Vars[cmd],strtok(cmdtext, Vars[idx]));
	
	SendMsg(playerid,"You used some command.");
	
	if (OnPlayerCommandTextProp(playerid, cmdtext)) { return 1; }

	return 0;
}


// At some other file -->
public OnPlayerCommandTextProp(playerid, cmdtext[])
{
	enum PVarsEnum
	{
	    Pcmd[256],
	    Pstring[256],
	    Ppname[MAX_PLAYER_NAME],
	    Penc_pname[256],
	    Ppropowner[256],
	    Ppropname[256],
	    Ptmp[256],
	    Ptmp2[256],
	    Plist,
	    Pidx
	}
	
	new PVars[PVarsEnum];

	SendMsg(playerid,"Test 1");
	set(PVars[Ppname],PlayerName(playerid));
	SendMsg(playerid,"Test 2");
	set(PVars[Penc_pname],udb_encode(PVars[Ppname]));
	SendMsg(playerid,"Test 3");
	set(PVars[Pcmd],strtok(cmdtext, PVars[Pidx]));
	
	if (strcmp(PVars[Pcmd], "/moo", true) == 0)
	{
		SendMsg(playerid,"UhUh");
		return 1;
	}
	return 0;
}


Functions wich most likely will cause the problems:

public udb_encode(nickname[]) {
  new enctmp[MAX_STRING];
  set(enctmp,nickname);
  enctmp=strreplace("_"," 00",enctmp);
  enctmp=strreplace(";"," 01",enctmp);
  enctmp=strreplace("!"," 02",enctmp);
  enctmp=strreplace("/"," 03",enctmp);
  enctmp=strreplace("\\"," 04",enctmp);
  enctmp=strreplace("["," 05",enctmp);
  enctmp=strreplace("]"," 06",enctmp);
  enctmp=strreplace("?"," 07",enctmp);
  enctmp=strreplace("."," 08",enctmp);
  enctmp=strreplace("*"," 09",enctmp);
  enctmp=strreplace("<"," 10",enctmp);
  enctmp=strreplace(">"," 11",enctmp);
  enctmp=strreplace("{"," 12",enctmp);
  enctmp=strreplace("}"," 13",enctmp);
  enctmp=strreplace(":"," 14",enctmp);
  enctmp=strreplace("="," 15",enctmp);
  return enctmp;
}

Functions used by the function above:

strreplace(trg[],newstr[],src[]) {
 new repf=0;
 new reps1[MAX_STRING];
 new reptmp[MAX_STRING];
 set(reps1,src);
 repf = strfind(reps1,trg);
 reptmp[0]=0;
 while (repf>=0)
    {
		strcat(reptmp,ret_memcpy(reps1, 0, repf));
		strcat(reptmp,newstr);
		reps1=ret_memcpy(reps1, repf+strlen(trg), strlen(reps1)-repf);
        	repf = strfind(reps1,trg);
    }
 strcat(reptmp,reps1);
 return reptmp;
}

ret_memcpy(const source[],index=0,numbytes) {
SendClientMessageToAll(0xFF0000FF,"TEST 1");
  new rettmp[MAX_STRING];
  new reti=0;
  rettmp[0]=0;
  SendClientMessageToAll(0xFF0000FF,"TEST 2");
  if (index>=strlen(source)) return rettmp;
  if (numbytes+index>=strlen(source)) numbytes=strlen(source)-index;
  if (numbytes<=0) return rettmp;
  for (reti=index;reti<numbytes+index;reti++) {
	rettmp[reti-index]=source[reti];
	if (source[reti]==0) return rettmp;
  }
  SendClientMessageToAll(0xFF0000FF,"TEST 3");
  rettmp[numbytes]=0;
  return rettmp;
}