VB.NET Regular Expressions

Thanks for the statement.
New problem: System.Text.RegularExpression is not recognized. I assume that I'm missing an install component. Is this correct?

It's System.Text.RegularExpressions not System.Text.RegularExpression

Function RegExpTest(ByVal patrn, ByVal strng)
Dim regEx, retVal ' Create variable.
regEx = New Regex()
regEx.Pattern = patrn ' Set pattern.
regEx.IgnoreCase = False ' Set case sensitivity.
retVal = regEx.Test(strng) ' Execute the search test.
If retVal Then
RegExpTest = "One or more matches were found."
Else
RegExpTest = "No match was found."
End If
End Function
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRegExp.Click
MsgBox(RegExpTest("is.", "IS1 is2 IS3 is4"))
End Sub
When I build this code, I get the message
C:\CS391\NA07\Form1.vb(119): Overload resolution failed because no accessible 'New' accepts this number of arguments.
Then, if I make this change
regEx = New Regex(patrn) ' Just to give it any parameter
it will then clean compile, but when I execute it gives
An unhandled exception of type 'System.MissingMemberException' occurred in microsoft.visualbasic.dll
Additional information: Public member 'Pattern' on type 'Regex' not found.
Sooooo, advice, please!