why is it so that I cant i top up a colour videotape but one can replenish a black n white videotape?

why is it so that I cant i top up a colour videotape but one can replenish a black n white videotape?

You should know how to. They usually have 3 holes which you requirement to unblock (push the plastic in). Then you can work out which colour is which base on the order of the colours on the print come first. Then just crawl each near the relevant colour, but be careful not to overfill it. Make sure you put one of those litlte rubber plugs surrounded by each hole again, and I usually stick a bit of video over the top just to trade name sure they don't come out again.
You can refill a color videotape. They have color ink refill available, however they suck and you're better off buying modern color cartridges from Walmart or Target. I tried to refill my tape and the ink looked crazy! I was feed up and went to Target the subsequent morning for a new HP catridge! It be cheaper than the clean up I'd own to deal near with that stupid messy gear.
go to www.inktec.com and check for restock instructions on the model of ur cartridge