>.... There is no errors in program. ....
LOL First programm of this type I've heard of.
The problem is are you 100% shure strange input can not result into such stuff? SRTG+0 on a text box can cause havoc, for example.
Agnes
Words are given to man to enable him to conceal his true feelings.
Charles Maurice de Talleyrand-Périgord
Weeks of programming can save you hours of planning.
OffThere is no place like [::1]