Problem with my monitoring speakers

[FailsafeRecords]

Hi guys.

Actually i have problems with my monitoring speakers, let me explain with a concrete exemple: I was recording a cover of A steady decline by ATB , and when the last riff comes in , there normally is a pan, and with my speakers i only hear the right guitar, but not the left. but what i don't understand is when the two guitars are played together on other parts , i can hear both of them.

i hope you understand my problems , is the bit complicated to explain.

Thanks a lot