Free Con A from Con A-Sepharose (Sigma)

[somchai]

Dear Everyone,
        I tried to separate glycoproteins using Con A -Sepharose in an  open
column.   In the first step  I equilibrated the column (1ml of ConA-Sepharose
 from Sigma  onto 1cmx 5cm sigma column) with lectin column buffer about 6 ml. 
        I found a lot of free Concanavalin A passing through the column.( 4
bands on 12%SDS-PAGE, silver stained) The first band (~24kDa) has a size of
about 3mm.X 5mm. for 5microlitres. 

 Is it usual that we will have that amount of free Con A out off Sepharose?

        Without luck, I haven't got any extra bands in my elution fractions
with either 10mM Methyl-alpha-D- glucoside or 500mM
Methyl-alpha-D-mannoside. What went wrong? 

        All  suggestions would be greatly  appreciated.
        Thank you very much in advance.
        Mr Somchai Sangamnadech