Stored Procedure Not Returning Results

Hi,
I'm creating a stored procedure that pulls information from 4 tables based on 1 parameter. This should be very straightforward, but for some reason it doesn't work.
Given below are the relevant tables:
  SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[tbl_Project](
[ProjID] [varchar](300) NOT NULL,
[ProjType] [varchar](20) NULL,
[ProjectTitle] [varchar](max) NULL,
[ProjectDetails] [varchar](max) NULL,
[ProjectManagerID] [int] NULL,
[RequestedBy] [varchar](max) NULL,
[DateRequested] [datetime] NULL,
[DueDate] [datetime] NULL,
[ProjectStatusID] [int] NULL,
CONSTRAINT [PK__tbl_Project__0B91BA14] PRIMARY KEY CLUSTERED
(
[ProjID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF
GO
ALTER TABLE [dbo].[tbl_Project] WITH CHECK ADD CONSTRAINT [FK_tbl_Project_tbl_ProjectManager] FOREIGN KEY([ProjectManagerID])
REFERENCES [dbo].[tbl_ProjectManager] ([ProjectManagerID])
GO
ALTER TABLE [dbo].[tbl_Project] CHECK CONSTRAINT [FK_tbl_Project_tbl_ProjectManager]
GO
ALTER TABLE [dbo].[tbl_Project] WITH CHECK ADD CONSTRAINT [FK_tbl_Project_tbl_ProjectStatus] FOREIGN KEY([ProjectStatusID])
REFERENCES [dbo].[tbl_ProjectStatus] ([ProjectStatusID])
GO
ALTER TABLE [dbo].[tbl_Project] CHECK CONSTRAINT [FK_tbl_Project_tbl_ProjectStatus]


-----------------------------------------------------------------


SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[tbl_Report](
[ReportName] [varchar](50) NOT NULL,
[ProjID] [varchar](300) NULL,
[DeptCode] [varchar](50) NULL,
[ProjType] [varchar](50) NULL,
[ProjectTitle] [varchar](500) NULL,
[ProjectDetails] [varchar](3000) NULL,
[ProjectManagerID] [int] NULL,
[RequestedBy] [varchar](50) NULL,
[DateRequested] [datetime] NULL,
[DueDate] [datetime] NULL,
[ProjectStatusID] [int] NULL,
CONSTRAINT [PK_tbl_Report] PRIMARY KEY CLUSTERED
(
[ReportName] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF
GO
ALTER TABLE [dbo].[tbl_Report] WITH CHECK ADD CONSTRAINT [FK_tbl_Report_tbl_ProjectManager] FOREIGN KEY([ProjectManagerID])
REFERENCES [dbo].[tbl_ProjectManager] ([ProjectManagerID])
GO
ALTER TABLE [dbo].[tbl_Report] CHECK CONSTRAINT [FK_tbl_Report_tbl_ProjectManager]
GO
ALTER TABLE [dbo].[tbl_Report] WITH CHECK ADD CONSTRAINT [FK_tbl_Report_tbl_ProjectStatus] FOREIGN KEY([ProjectStatusID])
REFERENCES [dbo].[tbl_ProjectStatus] ([ProjectStatusID])
GO
ALTER TABLE [dbo].[tbl_Report] CHECK CONSTRAINT [FK_tbl_Report_tbl_ProjectStatus]


--------------------------------------------------------------


SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[tbl_ProjectStatus](
[ProjectStatusID] [int] IDENTITY(1,1) NOT NULL,
[ProjectStatus] [varchar](max) NULL,
CONSTRAINT [PK__tbl_ProjectStatu__023D5A04] PRIMARY KEY CLUSTERED
(
[ProjectStatusID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF


-----------------------------------------------------------


SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[tbl_ProjectManager](
[ProjectManagerID] [int] IDENTITY(1,1) NOT NULL,
[FName] [varchar](50) NULL,
[LName] [varchar](50) NULL,
[Inactive] [int] NULL,
CONSTRAINT [PK__tbl_ProjectManag__7D78A4E7] PRIMARY KEY CLUSTERED
(
[ProjectManagerID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF

 
And here is the stored procedure that I wrote (doesn't return results):
  SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[GetReportQuery]
(
@ReportName varchar(100)
)

AS

BEGIN

SET
NOCOUNT ON

IF @ReportName IS NULL
BEGIN
RETURN -1
END
ELSE
BEGIN

DECLARE @DeptCode varchar(50), @ProjID varchar(50)
SELECT @DeptCode = DeptCode FROM tbl_Report WHERE ReportName = @ReportName

SET @ProjID = @DeptCode + '-' + '%'

SELECT P.ProjID, P.ProjType, P.ProjectTitle, P.ProjectDetails, M.FName, M.LName, P.DateRequested, P.DueDate, S.ProjectStatus
FROM tbl_Project P, tbl_ProjectManager M, tbl_ProjectStatus S
WHERE ((P.ProjID = (SELECT ProjID FROM tbl_Report WHERE ((ReportName = @ReportName))))
AND (P.ProjectDetails = (SELECT ProjectDetails FROM tbl_Report WHERE ReportName = @ReportName) OR P.ProjectDetails IS NULL)
AND (M.FName = (SELECT FName FROM tbl_ProjectManager WHERE (ProjectManagerID = (SELECT ProjectManagerID FROM tbl_Report WHERE ReportName = @ReportName))) OR M.FName IS NULL)
AND (M.LName = (SELECT LName FROM tbl_ProjectManager WHERE (ProjectManagerID = (SELECT ProjectManagerID FROM tbl_Report WHERE ReportName = @ReportName))) OR M.LName IS NULL)
AND (P.DateRequested = (SELECT DateRequested FROM tbl_Report WHERE ReportName = @ReportName) OR P.DateRequested IS NULL)
AND (P.DueDate = (SELECT DueDate FROM tbl_Report WHERE ReportName = @ReportName) OR P.DueDate IS NULL)
AND (S.ProjectStatus = (SELECT ProjectStatusID FROM tbl_Report WHERE ReportName = @ReportName) OR S.ProjectStatus IS NULL)
)
END

END 
Can someone see what's wrong? 
Thanks.