Ошибка "'is not a valid floating point value"

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
#include <Math.hpp>
#include "math.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormCreate(TObject *Sender)
{
StringGrid2->Cells[0][0]="med";
StringGrid2->Cells[1][0]="sred";
}
//---------------------------------------------------------------------------
void __fastcall TForm1::РасчетClick(TObject *Sender)
{
float x,a[10][12],sum=0,max=-1e23,min=1e23,med;
int i,j,sumsch=0;
x=StrToFloat(Edit1->Text);
 
for (i = 0; i <= StringGrid1->ColCount; i++)
for (j = 0; j <= StringGrid1->RowCount; j++) {
 
}
{
a[i][j]=StrToFloat(StringGrid1->Cells[i][j]);
}
 
for (i = 0; i <= StringGrid1->ColCount; i++)
for (j = 0; j <= StringGrid1->RowCount; j++)
 {
 
    if((i+j)<=x){sum+=a[i][j];
                 sumsch++;
 
                 }
    else a[i][j]=0;
 
 }
       sum=sum/sumsch;
        float sumd = SimpleRoundTo(sum, -2);
       for (i = 0; i <= StringGrid1->ColCount; i++)
       for (j = 0; j <= StringGrid1->RowCount; j++)
       {
           if (a[i][j]>=max) max=a[i][j];
           if ((a[i][j]<=min)&&(a[i][j]!=0)) min=a[i][j];
 
       }
       med=(max+min)/2;
       float medd = SimpleRoundTo(med, -2);
 
    StringGrid2->Cells[0][1]=sumd;
    StringGrid2->Cells[1][1]=medd;
 
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Edit2Change(TObject *Sender)
{
int sz;
sz=StrToInt(Edit2->Text);
StringGrid1->ColCount=sz;
 
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::Edit3Change(TObject *Sender)
{
 int szz;
szz=StrToInt(Edit3->Text);
StringGrid1->RowCount=szz;
}
//---------------------------------------------------------------------------

x=StrToFloat(Edit1->Text);

a[i][j]=StrToFloat(StringGrid1->Cells[i][j]);

for (i = 0; i <= StringGrid1->ColCount; i++)

for (i = 0; i < StringGrid1->ColCount; i++)