Only one expression can be specified in the select list when the subquery is not introduced with EXISTS error in sql query

insert into #tmpImportTruckMin(
Month,
Count,
ID,
ContainerSize,
TruckTime,
ContainerOrder
) 
values
(
(
 SELECT (case when @monthnoImportTime = 1 then 'Jan' 
              when @monthnoImportTime = 2 then 'Feb' 
              when @monthnoImportTime = 3 then 'Mar' 
              when @monthnoImportTime= 4 then 'Apr' 
              when @monthnoImportTime = 5 then 'May' 
              when @monthnoImportTime= 6 then 'Jun' 
              when @monthnoImportTime = 7 then 'Jul' 
              when @monthnoImportTime= 8 then 'Aug' 
              when @monthnoImportTime = 9 then 'Sep' 
              when @monthnoImportTime = 10 then 'Oct' 
              when @monthnoImportTime = 11 then 'Nov' 
              when @monthnoImportTime = 12 then 'Dec' end
        ),
 ISNULL(COUNT(GatePassId),0),
 @monthnoImportTime,
 '20FT', 
  AVG(
    CASE 
    WHEN Status = 'In Yard' thenISNULL(DATEDIFF(MINUTE,TimeIn,getdate()),0)  
    when status = 'Left The Yard' then ISNULL(DATEDIFF(MINUTE,TimeIn,TimeOut),0) 
    else '0' end
     ),
1
from tbl_CMS_GatePass 
where MONTH(AddedTime) = @monthnoImportTime 
and YEAR(AddedTime) = @Year 
and DepotID =@DepotID 
and BranchID = @branchID
AND ((ShippingLine IS NULL OR ShippingLine=0) AND (@ShippingLine IS NULL OR @ShippingLine=0) OR ShippingLine= CASE WHEN ((@ShippingLine=0) OR (@ShippingLine IS NULL)) THEN ShippingLine ELSE @ShippingLine END)
and ((Customer IS NULL OR Customer=0) AND (@Client IS NULL OR @Client=0) OR Customer= CASE WHEN ((@Client=0) OR (@Client IS NULL)) THEN Customer ELSE @Client END) and ContainerSize = 2))