iejun:
aa ok thx ..will try something different. Am looking for a reference on which pins are taken by the shield but cant find it online ...
What does the manufacturer of the shield say?
You can look in the SFEMP3Shield library sources to see that it uses pins 2, 6, 7, and 8 on most Arduino boards. As an SPI device it also use pins 11, 12, and 13 on most Arduino boards and Pin 10 has to be kept as an OUTPUT.
An SD reader is an SPI device so it shares 11, 12, and 13 on most Arduino boards and has a fourth pin for Slave Select. Any free digital pin will work.
The PWM Shield is an I2C/TWI/Wire device which uses A4 and A5 on most Arduino boards.