Dryer will not ignite. Checked the regulator: is good .the igniter is good. Can't seem to find the problem

Is power getting to the ignitor? Does the ignitor get hot? If not, you need to trace through the thermostat(s) and interlocks to see where the power "disappears".

If the ignitor is getting hot, then it's probably the gas valve. Is there power to the valve? If not, you need to trace that down. If there is power to the valve, the valve or the coil that operates the valve is likely faulty.