Whats wrong with my indicator? Error Message

[Forex Trader]

Hi,
here is the code from my indicator:

#property indicator_separate_window
#property indicator_buffers 2
#property indicator_color1 LightSeaGreen
#property indicator_color2 Blue

extern string Timeframe_Momentum = "PERIOD_H1";
extern int Periode_Momentum = 500;
extern int Periode_MA_Momentum = 8;

double Buffer_Mom[];
double Buffer_Ma[];

int init()
{
//---- indicators
SetIndexStyle(0,DRAW_LINE);
SetIndexStyle(1,DRAW_LINE);
SetIndexBuffer(0,Buffer_Mom);
SetIndexBuffer(1,Buffer_Ma);

//----
SetIndexEmptyValue(0,0.0);
SetIndexEmptyValue(1,0.0);

SetIndexDrawBegin(0,100);
SetIndexDrawBegin(1,100);

//----
return(0);
}


int deinit()
{

//----
return(0);
}

void start()
{

int counted_bars=IndicatorCounted();
int limit=Bars-counted_bars;
if(counted_bars>0) limit++;
//----
for(int i=0; i<limit; i++)
{
Buffer_Mom[i]=iMomentum(NULL,Timeframe_Momentum,Periode_Momentum,PRICE_CLOSE,i);
Buffer_Ma[i]=iMAOnArray(Buffer_Mom,0,Periode_MA_Momentum,0,MODE_SMA,i);


}

return(0);
}

Here is the code I use in the main Programm:
double GMI1 = iCustom(NULL,0,"GMI",Timeframe_Momentum,Periode_Momentum,Periode_MA_Momentum, 0,1);
double GMI2 = iCustom(NULL,0,"GMI",Timeframe_Momentum,Periode_Momentum,Periode_MA_Momentum, 1,2);

Now my problems:
I get this error message: EURUSD,M5: invalid integer number as parameter 2 for Indicator call function
AND there is no Buffer_Ma[i] in my chart! What is wrong with my code?!