|Sounds like a jumper problem.|
I assume you've got the 'twisted cable' for the floppies? The a: drive goes after the twist, at the end of the cable. The b: drive goes on the middle connector.
Floppy drives have drive select (DS) jumpers. They can have as many as 4. When there's 4 they're numbered either from DS0 to DS3 or from DS1 to DS4. You want it jumpered at the second selection--DS1 or DS2 depending on how they're numbered.
Most newer 1.44's are hardwired at the second DS so you normally don't need to worry about them, unless yours is different and you've changed its jumper.
The jumpering is different if you're using a non-twisted cable. Then drive a: is the first DS and drive b: is the second DS and their position on the cable is irrelevent.
Onward to 300