BII not shifting out of first.

[Daniel T.]

hey guys mi flexplate got grenaded a few days ago and i changed it, but when i bolted everything back, my tranny wont shift out of 1st gear.starts fine, you can even drive it for a couple blocks on first,but then nothing, no shifting to any other gear.what could be wrong? already checked oil level,changed modulator,cleaned governor, everything seems to be in its place.friend of mine said it could be the valvebody, you think?what could be the problem there? i really appreciate your help cuase im already clueless:icon_confused: