Problem To Insert A Double Value Into Sqlexpress

Hi..

I have a small problem to insert a double value into a sqlexpress database:

Her is the problem example

dblValue = 5.5
int = 1

conn.Open()
Dim query As String = "INSERT INTO testtable VALUES(" & intValue & "," & dblValue & ",1.2)"
Dim command As SqlCommand = New SqlCommand(query)
Command.Connection = conn
command.ExecuteNonQuery()

The table has tre columns: int, decimal, decimal.
"INSERT INTO testtable VALUES(1,5,5,1.2)"

The problem is that ,in the sqlcommand, the dblValue er transformed from 5.5 to 5,5, so it seems that i am going to insert 4 values, 1 - 5 - 5 and 1.2. Why are the dblvalue transformed and not the value 1.2? How do I avoid this problem?