Lectins have specificity for particular sugars. You may need different lectins to detect different glycoproteins if they have different types of glycosylation.
If you know the glycoprotein contains an abundant amount of a particular sugar residue, you may use a single lectin. We have been purifying an oviduct-specific glycoprotein synthesized and secreted by secretory cells of the oviduct in hamsters. We know that it is a highly glycosylated protein with a lot of N-acetyl-galactosamine residues. Base on this information, we have been successfully using Helix pomatia agglutinn (HPA)-agarose to purify the glycoproteins from hamster oviducts.