'The INSERT statement conflicted with the FOREIGN KEY constraint

Question

I am wanting to add insert into my uspInsertUserRoles procedure:

CREATE PROCEDURE [dbo].[uspInsertUserRoles]
    @RoleID INT,
    @UserID INT
    AS
    BEGIN
        INSERT INTO tblUserRoles(RoleID, UserID)
        VALUES (@RoleID,@ UserID)
    END
GO

Table:

CREATE TABLE [dbo].[tblUserRoles](
    [UserRoleID] [int] IDENTITY(1,1) NOT NULL,
    [UserID] [int] NOT NULL,
    [RoleID] [int] NOT NULL,
PRIMARY KEY CLUSTERED 
(
    [UserRoleID] ASC
)WITH (STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[tblUserRoles]  WITH CHECK ADD FOREIGN KEY([RoleID])
REFERENCES [dbo].[tblRoles] ([RoleID])
GO

ALTER TABLE [dbo].[tblUserRoles]  WITH CHECK ADD FOREIGN KEY([UserID])
REFERENCES [dbo].[tblUsers] ([UserID])
GO

This is my code:

Private Sub btnInsertUserRole_Click(sender As Object, e As EventArgs) Handles btnInsertUserRole.Click
        sqlCon = New SqlConnection(strConn)

        Using (sqlCon)
            Dim sqlComm As New SqlCommand()
            Dim msg As String = "EXEC sp_addrolemember '" & storedRoleDesc & "','" & storedUserName & "'"
            MessageBox.Show(msg)
            sqlComm.Connection = sqlCon
            sqlComm.CommandText = "uspInsertUserRoles"
            sqlComm.CommandType = CommandType.StoredProcedure

            sqlComm.Parameters.AddWithValue("UserID", storedUserID)
            sqlComm.Parameters.AddWithValue("RoleID", storedRoleID)

            sqlCon.Open()
            'sqlComm.ExecuteNonQuery()

            Dim rowsAffected As Integer = sqlComm.ExecuteNonQuery()
            MessageBox.Show(rowsAffected)
            If rowsAffected > 0 Then
                MessageBox.Show("Record has been inserted successfully")
            End If

Gives me error:

System.Data.SqlClient.SqlException: 'The INSERT statement conflicted with the FOREIGN KEY constraint "FK__tblUserRo__UserI__51300E55". The conflict occurred in database "THISONE", table "dbo.tblUsers", column 'UserID'. The statement has been terminated.'

My tblUsers:

CREATE TABLE tblUsers(
        UserID INT IDENTITY(1,1),
        FirstName varchar(50) NOT NULL,
        LastName varchar(50) NOT NULL,
        Age int NOT NULL,
        UserName varchar(50) NOT NULL,
        Password varchar(50) NOT NULL,
        PRIMARY KEY (UserID),
        UNIQUE(UserName)
        )