Shapiro time delay is caused by refraction. Gravitational time dilation does not exist.
' The Shapiro time delay effect, or gravitational time delay effect, is one of the four classic Solar System tests of general relativity . Radar signals passing near a massive object take slightly longer to travel to a target and longer to return than they would if the mass of the object were not present. The time delay is caused by time dilation , which increases the time it takes light to travel a given distance from the perspective of an outside observer. [...] ' Throughout this article discussing the time delay, Shapiro uses c as the speed of light and calculates the time delay of the passage of light waves or rays over finite coordinate distance according to a Schwarzschild solution to the Einstein field equations .'- Wikipedia And, just like Pound and Rebka, completely ignores refraction. Which makes his whole calculation wrong, because he does not understand basic physics, which require to take into consideration the index of refraction, which