SqlException: Arithmetic overflow error for data type tinyint, value = -1

I have been trying to pass an int with the value of 1 to my stored procedure but I keep getting an exception of "Arithmetic overflow error for data type tinyint, value = -1." The Value of the int is 1 but the exception says its -1 which I dont understand why. Anyway I have posted the code below. I am probably missing something obvious.

.net Code

protected void btnUpdate_Click(object sender, EventArgs e)
    {
        string result = "";
        string currentFileName = (string)(Session["FileName"]);
        string FileName = txtUploadStatus.Text;
        string sSQL = "usp_imageloader_update";
        int ImgID = (int)(Session["ImgID"]);

        using (SqlConnection dbConnection = new SqlConnection(CKS_app_settings.sql_conn_string_db))
        {
            // SqlTransaction tn=null;   
            try
            {
                dbConnection.Open();
                //start Transaction
                // tn = dbConnection.BeginTransaction();
                SqlCommand command = new SqlCommand(sSQL, dbConnection);
                //command.Transaction = tn;
                command.CommandText = sSQL;
                command.CommandType = CommandType.StoredProcedure;
                command.CommandTimeout = 1024;
int Active = 0;

                if (chkActive.Checked == true)
                {
                    Active = 1;
                }
                else
                {

                }

                if (currentFileName != FileName)
                {
                    // Split entire file path to grab filename
                    string[] split = txtUploadStatus.Text.Split(new char[] { '\\' });
                    FileName = split[06];
                }
                else
                {
                    FileName = txtUploadStatus.Text;
                }

                command.Parameters.AddWithValue("@p_image_id", ImgID);
                command.Parameters.AddWithValue("@p_filename", FileName);
                command.Parameters.AddWithValue("@p_Active", Active);
                command.Parameters.AddWithValue("@p_url", txtUrl.Text);
                command.Parameters.AddWithValue("@p_Title", txtImgTitle.Text);
                command.Parameters.AddWithValue("@p_alt_text", txtAlt.Text);
                int rowsAffected = command.ExecuteNonQuery();
            }
            catch (SqlException ex)
            {
               // throw ex;

                //If it failed for whatever reason, rollback the //transaction
                //tn.Rollback();                          
                //No need to throw because we are at a top level call and //nothing is handling exceptions
                result = ex.InnerException.Message;
            }

Stored Procedure

USE [smsdb_test_griffin2]
GO
/****** Object:  StoredProcedure [dbo].[usp_imageloader_update]    Script Date: 01/09/2012    08:52:01 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER    procedure [dbo].[usp_imageloader_update]
@p_image_id INT,
@p_filename VARCHAR(100),
@p_Active TINYINT,
@p_url  VARCHAR(255),
@p_Title VARCHAR(100),
@p_alt_text VARCHAR(255)
as 

UPDATE Image_Library_UK 
SET  
Image_name=@p_filename,
Active=-@p_Active,
Url=@p_url,
Alt_text=@p_alt_text 

WHERE Image_id=@p_image_id