string.Substring(); Index and length must refer to location

Question

Hi,

 

i got the error in below code. what i did wrong...

 

Error : Index and length must refer to a location within the string.\r\nParameter name: length

 

Code :

  

int l1 = elespt[0].Length - 50;

int l2 = elespt[0].Length - 1;

string val = elespt[0].ToString();

p1 = val.Substring(l1, l2);

 

 

elespt[0] is " this page, it means the vendor you purchased this e-book from did not deliver the correct file. Please contact ".

 

Thanks in Advance.