Pattern tiling from photoshop to illustrator

Hi I have made a tile pattern in photoshop and it fits perfectly creating a large pattern. I need to transfer this into illustrator creating it into a vector tile pattern so it can be blown up. When I transfer this pattern into illustrator from photoshop and vectorise it, it doesn't match up and create a seamless pattern. Is this due to changing to   a vector? The pattern is slightly out in illustrator but its absolutely perfect in photoshop. Is there any way of creating this tiled file into vector and also matching up every line to create a tile pattern? Is this possible? Thanks