SQL problem, stressing me

Hi, Can somebody please help me with this. When i execute it, it says cannot convert varchar value 'jgj' to datatype int and NULL's the staffID

Please help

ALTER

PROCEDURE [dbo].[addAssignedMilestone]

(

@JobID

ASINT,

@Milestone

ASVARCHAR(500),

@TargetDate

ASDATETIME,

@StaffName

ASVARCHAR,

@ActualDate

ASDATETIME,

@Memo

ASVARCHAR(500)

)

AS

DECLARE

@ID ASint

DECLARE

@MilestoneID ASINT

DECLARE

@StaffID asINT

SET

@ID = 0

SET

@MilestoneID =(SELECT ID FROM tblMilestones WHERE Milestone = @Milestone)

SET

@StaffID =(SELECT ID from tblStaff WHERE surname +', '+ forename = @StaffName)

BEGIN

INSERT

INTO tblAssignedMilestones(JobID,MilestoneID, TargetDate, AssignedStaffID, ActualDate, Memo)

VALUES

(@JobID,@MilestoneID, @TargetDate,@StaffID, @ActualDate,@Memo)

SELECT

@ID =Max(ID)

FROM tblAssignedMilestones

WHERE JobID = @JobID AND @Milestone =(SELECT ID FROM tblMilestones WHERE Milestone = @Milestone)

END

SELECT

@ID

EXEC

addAssignedMilestone101,'jgj','01-Apr-2013','Smith, Pete','02-Apr-2013','m'

ALTER

PROCEDURE [dbo].[addAssignedMilestone]

(

@JobID

ASINT,

@Milestone

ASVARCHAR(500),

@TargetDate

ASDATETIME,

@StaffName

ASVARCHAR,

@ActualDate

ASDATETIME,

@Memo

ASVARCHAR(500)

)

AS

DECLARE

@ID ASint

DECLARE

@MilestoneID ASINT

DECLARE

@StaffID asINT

SET

@ID = 0

SET

@MilestoneID =(SELECT ID FROM tblMilestones WHERE Milestone = @Milestone)

SET

@StaffID =(SELECT ID from tblStaff WHERE surname +', '+ forename = @StaffName)

BEGIN

INSERT

INTO tblAssignedMilestones(JobID,MilestoneID, TargetDate, AssignedStaffID, ActualDate, Memo)

VALUES

(@JobID,@MilestoneID, @TargetDate,@StaffID, @ActualDate,@Memo)

SELECT

@ID =Max(ID)

FROM tblAssignedMilestones

WHERE JobID = @JobID AND @Milestone =(SELECT ID FROM tblMilestones WHERE Milestone = @Milestone)

END

SELECT

@ID

EXEC

addAssignedMilestone101,'jgj','01-Apr-2013','Smith, Pete','02-Apr-2013','m'