Conversion problem - (Jan/19/2012 )

How to convert ng/ul to pmol/ml.
this is regarding to oligonucleotide probe with a MW of 17709g/mol.

Please help me in this conversion

Thanx in advance

Use concentration (c) = number of moles (n) / volume (v) and n= mass (m) / molar mass (M_r). Remember to keep the units consistent!