He wanted them to help fund the Bishop's war
Charles I was trying to reform the Church of England and the various churches throughout the UK (including Scotland) to make them more Catholic. He had appointed William Laud as Archbishop who was introducing things like candles and icons to churches.
Many people in Scotland were opposed to these reforms as they followed a presbyterian system of church governance (elders and elected councils running the church) and were often Calvinists (a form of Protestantism - thus opposed to Catholicism). Charles and Laud's attempt to enforce the Anglican Book of Common Prayer (which dictated how people should pray and worship) was a bit of a deal breaker and led to the outbreak of a war between Scotland and Charles I - the Bishops War.
Charles I needed money to help finance this war, but at the time, the King was unable to raise tax or control finance without the help of parliament, so he was forced to recall parliament to ask them for help raising the money.
Understandably, parliament was a bit annoyed about having been ignored during the"11 years tyranny" from 1929-40 and so instead of helping him get money, they focused on addressing the issue of how far the King's power should extend. Charles wasn't impressed... so he dissolved parliament again hence the name "the Short Parliament" (it only lasted 3 weeks!).
Parliament was then recalled a second time in 1940. This time because Charles had lost the Bishops war and was therefore faced with heavy reparations (money he had to pay to the Scottish victors as a sort of compensation). To avoid the previous issue of being dismissed again, parliament passed an act that meant they could only be dissolved with the agreement of the members. Therefore, it didn't officially end until around 1653 when Cromwell became lord protector (although technically you could argue it wasn't until 1660 when the convention parliament took over to help prepare for Charles II's restoration).
Hope this helped! Let me know if I can do anything else:)