help with detector induction of pulses

[Hael]

hello someone could help, acquired a metal detector German (pulse matic xp 3000), trading house detector www.detectorhouse.com house, as is designed to penetrate to a depth of 12 meters with Table 1 m m but X 1 Indeed it has already probe into a tube of iron 6 inches that has more than 30 years of being buried and which lies at a depth of 1.40 meters and with the box or 1 x 1 fished much less so with the coil 18, "I do not know if the detector does not have this power or doing wrong things myself, the detector has a frequency ranging from 10 Hz to 20 kHz, according to discriminate metals, on the back brings a screw and a second led exclusive use of the manufacturer, apparently is a true copy of the press star detector II, to calibrate it is automatic and only (as the manual) should be programmed in the frequency with tic tac 5 per second, in the area (mexico) I am seeking burials are up to 3 meters deep, so it acquired, I am not alone there are more that what I have friends who are like me, I ask your help to know that is happening or the detector was nothing but a fraud for his understanding thanks, ojala and friend eric foster make a comment about this