I am new to the crosstab query. Can someone tell me what's wrong with the query below?

TRANSFORM Count(tblInvoice.cono) AS CountOfcono
SELECT tblInvoice.resname, Count(tblInvoices.cono) AS [Total Of cono]
FROM tblInvoices
GROUP BY tblInvoices.resname
PIVOT Format(gl_period,"mmm") In (
Format(DateAdd("m",0,Date()),"mmm"),
Format(DateAdd("m",-1,Date()),"mmm"),
Format(DateAdd("m",-2,Date()),"mmm"),
Format(DateAdd("m",-3,Date()),"mmm"),
Format(DateAdd("m",-4,Date()),"mmm"),
Format(DateAdd("m",-5,Date()),"mmm"),
Format(DateAdd("m",-6,Date()),"mmm"),
Format(DateAdd("m",-7,Date()),"mmm"),
Format(DateAdd("m",-8,Date()),"mmm"),
Format(DateAdd("m",-9,Date()),"mmm"),
Format(DateAdd("m",-10,Date()),"mmm"),
Format(DateAdd("m",-11,Date()),"mmm"))

I am getting this error --

Missing ), ], or item in query expression 'Format(gl_period, "mmm") in (FormatDateAdd("m", 0, Date()'.

Thanks

SHK