Excel embeded IF statements - too many arguments error

I have the following series of If statements and I'm getting the error that there's too many arugments. I've checked some other posts with similar problems but can't see their problems within my statement. Essentially if the cell B2 contains a number month, I need it to perform a vlookup on a certain spreadsheet.

=if(B2=1,VLOOKUP(G2,'[Jan_Agent Hierarchy.xls]Sheet1'!$L$1:$U$4236,10,FALSE),if(B2=2,VLOOKUP(G2,'[feb_Agent Hierarchy.xls]Agent Hierarchy Details'!$L$2:$U$4214,10,FALSE), if(B2=3,vlookup(G2,'[mar_Agent Hierarchy.xls]Agent Hierarchy Details'!$L$1:$U$4262,10,FALSE), if(B2=4,VLOOKUP(G2,'[apr_Agent Hierarchy.xls]Agent Hierarchy Details'!$L$1:$U$4262,10,FALSE),if(B2=5,'[may_Agent Hierarchy.xls]Agent Hierarchy Details'!$L$1:$U$4234,10,FALSE),if(B2=6,VLOOKUP(G2,'[jun_Agent Hierarchy.xls]Agent Hierarchy Details'!$L$1:$U$4310,10,FALSE),if(B2=7,VLOOKUP(G2,'[jul_Agent Hierarchy.xls]Agent Hierarchy Details'!$L$1:$U$4322,10,FALSE),if(B2=8,VLOOKUP(G2,'[aug_Agent Hierarchy.xls]Agent Hierarchy Details'!$L$1:$U$4288,10,FALSE)))))