That's difficult to say - how do you know they aren't?
First off, run a copy of SQL Server Management Studio, and run a query listing all the rows in the employee table.
Then put a breakpoint on the line:
connetionString = "Data Source=JDPANDEY-PC;Initial Catalog=amsco;User ID = sa;Password=123";
Run you app in the debugger and click your button. When the debugger stops execution, single step through the code.
Do you get through each line and to the end of the method?
If not, then you should have a better idea where the problem is.
If you do, then run a second query in SSMS to list all rows, and compare the two lists. Is the new row in there?