Error 209 Ambiguous Column ..Transaction Count After EXECUTE Indicates .....

i'm getting following exception when i try to execute stored procedure.

{"Ambiguous column name 'MemberID'.
Transaction count after EXECUTE indicates that a COMMIT or ROLLBACK TRANSACTION statement is missing. Previous count = 0, current count = 1." }

I know why i'm getting "Ambiguous column name 'MemberID'" exception but i dont know why i'm getting
"Transaction count after EXECUTE indicates that......"

In my stored proc i'm checking if error occured goto :Error_handler where i do ROLLBACK TRAN

/* Its failing at MemberID = tTempResult.MemberID bcoz of Ambiguous column name. I know i have to use RebateInstanceItem.MemberID=tTempResult.MemberID */

here is my stored proc

CREATE PROCEDURE dbo.ExportFile
@intMonth INT,
@intYear INT,
@dtFirstDayOfMonth DATETIME

AS

BEGIN

BEGIN TRANSACTION


/*
I have some logic here that will select rows into temporary table
#TEMPRESULT
*/

UPDATE
dbo.RebateInstanceItem
SET
ResubmitCreated = @dtmNewCreated
FROM #TEMPRESULT tTempResult
WHERE
MemberID = tTempResult.MemberID
AND RebateInstanceItem.IsResubmit = 'Y'
AND (RebateInstanceItem.ResubmitCreated = @dtmLastCreated
OR RebateInstanceItem.ResubmitCreated IS NULL)

IF @@ERROR<>0
GOTO ERR_HANDLER // when error it will goto error_handler that will rollback

DROP TABLE #TEMPRESULT
IF @@ERROR<>0
GOTO ERR_HANDLER

COMMIT TRANSACTION
RETURN 0
END

ERR_HANDLER:
ROLLBACK TRANSACTION
RETURN 1
GO