Macbook only charges when asleep

My Macbook will only charge when asleep. When i open the lid the light turns to green and the battery symbol changes to the 'plug' icon but runs on battery power only. The battery was replaced about 3 months ago. I have tried resetting the SMC.

Any ideas please?

Neil

Model Name: MacBook
Model Identifier: MacBook1,1
Processor Name: Intel Core Duo
Processor Speed: 2 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache (per processor): 2 MB
Memory: 1 GB
Bus Speed: 667 MHz
Boot ROM Version: MB11.0061.B03
SMC Version: 1.4f12
Serial Number: 4H6365E2U9E

Could be a bad magsafe adapter. I just had a battery replacement and a magsafe adapter sent to me in one shot...