Digital Potentiometer and Power Supply

Hi, and thanks for helping me :)

I purchased Tusotek Auto DC-DC Constant Current Boost Buck Converter Voltage Regulator 6-35V to 1-35. I am trying to find digitally control the boost buck converter by replacing its 100K potentiometer with a 100K MCP41100 digital potentiometer. I tried using the digital potentiometer with Arduino and the DC-DC booster and it worked, but the booster does not go as high as with the original mechanical potentiometer. Would you know why I the digital potentiometer is no working as intended? What are the factors I must consider if I want to control boost buck converters with a digital potentiometer? Specs of the mechanical potentiometer can be found in the following website (scroll down): http://www.aliexpress.com/item/Trimpot-Trimmer-Potentiometer-3296-W-104-100K-VR-3296W-100K-ohm-Variable-Resistors-100pcs/1596795967.html

A schematic of the SMPS system would be helpful, since it would show how the resistor is used in circuit. The digital pot has a max voltage rating of around 5.5V, so it is possible you are exceeding that. Also, it powers up at half scale, so it would be advisable to make sure that a load is not connected until the output voltage is set,
cheers,
Richard