Error in sql server

Question

hi friends
 
 i m getting String or binary data would be truncated.error in sql sever 2008

my table is  PurchaseBill


PBNO                           int  (auto increment)       

PBDate        datetime

Supplier                    varchar(10) 

SupplierName          varchar(50)

Address            varchar(50)

BillNo                  int  (auto increment)

BillDate                datetime

PoNo                    varchar(10)

TotalAmount              numeric(12, 2)

DiscountPercent  numeric(12, 2)

DiscountAmount      numeric(12, 2)

NetAmount      numeric(12, 2)

NetAmountInWords  varchar(50)



i m inserting like this


INSERT INTO [PurchaseBill](PBDate,Supplier,SupplierName,Address,BillDate,PoNo,TotalAmount,DiscountPercent,DiscountAmount,NetAmount,NetAmountInWords)VALUES ('" + txtPbDate.Text + "','" + ddlSupplier.SelectedItem.ToString() + "','" + txtSupplierName.Text + "','" + txtSupplierAddress.Text + "','" + txtBillDate.Text + "','" + ddlPurchaseOrder.SelectedItem.ToString() + "','" + txtTotal.Text + "' ,'" + txtDiscount.Text + "','" + txtDiscountAmount.Text + "','" + txtNetAmount.Text + "','" + txtAmountInWords.Text + "')";


5/31/2012','112','MEHTA ASSOCIATES','GANDHINAGAR BANGALORE','5/31/2012','1',5267.10,10,526.71,4740.39,' Four Thousand Seven hundred Forty and Thirty Nine Paise Only.'

please help me frnds...its urgent...

  Thank u in advance..........